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1、 Global technical consultation report on proposed terminology for pathogens that transmitthrough the air Global technical consultation report on proposed terminology for pathogens that transmitthrough the airGlobal technical consultation report on proposed terminology for pathogens that transmit thr

2、ough the airISBN 978-92-4-008918-1(electronic version)ISBN 978-92-4-008919-8(print version)World Health Organization 2024Some rights reserved.This work is available under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0IGO licence(CCBY-NC-SA3.0IGO;https:/creativecommons.org/licenses/by-

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10、rea or of its authorities,or concerning the delimitation of its frontiers or boundaries.Dotted and dashed lines on maps represent approximate border lines for which there may not yet be full agreement.The mention of specific companies or of certain manufacturers products does not imply that they are

11、 endorsed or recommended by WHO in preference to others of a similar nature that are not mentioned.Errors and omissions excepted,the names of proprietary products are distinguished by initial capital letters.All reasonable precautions have been taken by WHO to verify the information contained in thi

12、s publication.However,the published material is being distributed without warranty of any kind,either expressed or implied.The responsibility for the interpretation and use of the material lies with the reader.In no event shall WHO be liable for damages arising from its use.Design and layout by Soph

13、ie Guetaneh Aguettant.This report is the result of an extensive collaborative effort and reflects shared agreement of the terminology between WHO and the esteemed four public health agencies:-Africa Centres for Disease Control and Prevention;-Chinese Center for Disease Control and Prevention;-Europe

14、an Centre for Disease Prevention and Control;-United States Centers for Disease Control and Prevention;This agreement underlines our collective commitment to moving forward together in implementing these statements.Statement of support iiiContentsAbbreviationsvAcknowledgementsviiTechnical Consultati

15、on Group viiChairs:viiMembers viiWHO Secretariat viiiOther external experts viiiOther WHO technical departments ixFinancial contributors ixExecutive summary xi1.Introduction12.Objectives,aim and scope33.Methods and processes54.Outcomes74.1 Modes of transmission 84.2 The term through the air transmis

16、sion 104.3 Exposure and its relationship to infection 114.4 Some factors affecting through the air transmission of IRPs and infection risk 114.5 Immediate practical implications 124.6 Key research gaps and next steps 135.Conclusions15References17Annexes25Annex 1.Governance structure 25Annex 2.Steps

17、in the technical consultation process 26Annex 3.Two processes undertaken for the consultation process 27Annex 4.Details,affiliations,expertise and roles of participants 29Annex 5.Summary of discussions 32Areas of overall general agreement 32Areas of non-consensus and concern regarding consequences 3

18、2 vAbbreviationsDescriptionAfrica CDCAfrica Centres for Disease Control and PreventionCDCCenters for Disease Control and Prevention,United States of AmericaCOVID-19Coronavirus Disease 2019IPCInfection Prevention and ControlIRPInfectious Respiratory Particle MERSMiddle East respiratory syndromePHEICP

19、ublic Health Emergency of International Concern PHSMPublic Health and Social Measures PPEPersonal Protective Equipment SARS-CoV-1Severe Acute Respiratory Syndrome Coronavirus 1 SARS-CoV-2Severe Acute Respiratory Syndrome Coronavirus 2 TBTuberculosisTCGTechnical Consultation GroupTTATThrough the air

20、transmissionWGWorking GroupAbbreviationsviiThe World Health Organization(WHO)would like to thank the many individuals who contrib-uted to the development of this document.This document was developed in consultation with the Technical Consultation Group on through the air transmission(TTAT).Technical

21、 Consultation Group The Technical Consultation Group on TTAT(November 2021 to present)included represent-atives from invited public health agencies(Africa Centres for Disease Control and Prevention,Chinese Center for Disease Control and Prevention,European Centre for Disease Prevention and Control,a

22、nd the United States Centers for Disease Control and Prevention)and others who were engaged in their personal capacity as experts in areas relevant to the consultation topic,as listed below.Chairs Gagandeep Kang(Christian Medical College,Vellore,India)and Yuguo Li(The University of Hong Kong,Hong Ko

23、ng SAR,China).Members Yewande Alimi(Africa Centres for Disease Control and Prevention,Addis Abba,Ethiopia),Yaseen Arabi(King Saud Bin Abdulaziz University for Health Sciences,Riyadh,Saudi Arabia),Julie Bennett(University of Otago,Wellington,New Zealand),Abdullah Assiri(Ministry of Health,Riyadh,Saud

24、i Arabia),Gautam Bhan(Indian Institute for Human Settlements,Ben-galuru,India),Arnab Bhattacharya(Tata Institute of Fundamental Research,Mumbai,India),Gabriel Birgand(Nantes University Hospital,Nantes,France),Lydia Bourouiba(Massachu-setts Institute of Technology,Cambridge,USA),Giorgio Buonanno(Univ

25、ersity of Cassino and Southern Lazio,Cassino,Italy),Cheryl Cohen(Centre for Respiratory Disease and Meningitis,National Institute for Communicable Diseases,South Africa),Benjamin Cowling(School of Public Health,The University of Hong Kong,Hong Kong SAR,China),David SC Hui(Stan-ley Ho Centre for Emer

26、ging Infectious Diseases,The Chinese University of Hong Kong,Hong Kong SAR,China),Michael Klompas(Harvard Medical School,Boston,USA),Nancy Leung(Faculty of Medicine,The University of Hong Kong,Hong Kong SAR,China),Li Liu(Tsinghua University,Beijing,China),Taronna Maines(the United States Centers for

27、 Disease Control and AcknowledgementsviiiPrevention,Atlanta,USA),Linsey Marr(Virginia Tech,Blacksburg,USA),Donald Milton(Uni-versity of Maryland School of Public Health,Maryland,USA),Lidia Morawska(Queensland University of Technology,Brisbane,Australia),Shiva Nagendra(Indian Institute of Technology,

28、Madras,India),Edward Nardell(Harvard Medical School,Boston,USA),Isabel Ochoa(Min-istry of Health,Lima,Peru),Jon Otter(Imperial College London,London,United Kingdom),Malik Peiris(School of Public Health,The University of Hong Kong,Hong Kong SAR,China),Diamantis Plachouras(European Centre for Disease

29、Prevention and Control,Solna,Sweden),Kevin Poggenpoel(South Africa Federation of Healthcare Engineering,Western Cape,South Africa),Hua Qian(Southeast University,Nanjing,China),Jacqui Reilly(Glasgow Caledonian University,Glasgow,United Kingdom),Chad Roy(National Primate Center,Tulane University,New O

30、rleans,USA),Shin-ichi Tanabe(Waseda University,Tokyo,Japan),Julian W.Tang(Uni-versity Hospitals of Leicester NHS Trust,Leicester Royal Infirmary,Leicester,United Kingdom),Raymond Tellier(McGill University,Montreal,Canada),Kwok Wai Tham(National Univer-sity of Singapore,Singapore),Richard Webby(St Ju

31、de Childrens Research Hospital,Memphis,USA),Dongqun Xu(National Institute of Environmental Health,Chinese Center for Disease Control and Prevention,Beijing,China),U Yanagi(Kogakuin University,Tokyo,Japan),Hui-Ling Yen(School of Public Health,The University of Hong Kong,Hong Kong SAR,China),Kwok-Yung

32、 Yuen(Department of Microbiology,The University of Hong Kong,Hong Kong SAR,China),Walter Zingg(Zurich University Hospital,Zurich,Switzerland).WHO Secretariat Lisa Askie,Thidar Pyone,Fatima Serhan(Science Division),Maria van Kerkhove(Health Emergencies Programme),under the leadership of Jeremy Farrar

33、(Science Division)(May 2023 onwards)(Soumya Swaminathan:Nov 2021 to Nov 2022).Other external expertsWe are grateful to Karen Grimmer(Stellenbosch University,Cape Town,South Africa)who undertook a living rapid review of evidence related to the transmission of SAR-CoV-2 through the air,as part of the

34、WHO Rapid Review Group.Acknowledgements go to the following additional external experts,who provided com-ments on different versions of the consultation report and/or attended some consultation meet-ings upon invitation(In alphabetical order of last name):Jameela Alsalman(Arabian Gulf University,Kin

35、g Hamad American Mission Hospital,Kingdom of Bahrain),Michael Bell(the United States Centers for Disease Control and Prevention,Atlanta,USA),Eeva Broberg(Euro-pean Centre for Disease Prevention and Control,Solna,Sweden),Colin Brown(United King-dom Health Security Agency,London,United Kingdom),Yehuda

36、 Carmeli(Tel Aviv Medical Centre,Israel),John Conly(IPC Foothills Medical Centre at Alberta Health Services,Alberta,Canada),Barry Cookson(University College London,London,United Kingdom),Nizam Damani(Public Health Agency,Northern Ireland,United Kingdom),Carole Fry(United King-dom Health Security Age

37、ncy,London,United Kingdom),Joost Hopman(Radboud University Medical Centre,Netherlands(Kingdom of the),Paul Hunter(University of East Anglia,East Anglia,United Kingdom),Mohammad Mushtuq Husain(Institute of Epidemiology,Disease Control&Research(IEDCR),Dhaka,Bangladesh),Kushlani Jayatilleke(Sri Jayewar

38、denepura General Hospital,Nugegoda,Sri Lanka),Devin Jopp(Association for Professionals in Infection Control and Epidemiology,USA),Souha Kanj(American University of Beirut Medical Center,Beirut,Lebanon),Annette Kraus(European Centre for Disease Prevention and Control,Solna,Sweden),Daniele Lantagne(Tu

39、fts University,USA),Fernanda Lessa(the United States Centers Global technical consultation report on proposed terminology for pathogens that transmit through the airix Acknowledgmentsfor Disease Control and Prevention,Atlanta,USA),Moi Lin Ling(Singapore General Hospi-tal,Singapore),Kalisvar Marimuth

40、u(National Centre for Infectious Diseases,NCID&Tan Tock Seng Hospital,Singapore),Geeta Mehta(Lady Hardinge Medical College and Associated Hospitals,New Delhi,India),Shaheen Mehtar(University of Stellenbosch,Infection Control Africa Network,Western Cape,South Africa),Ajibola Omokanye(European Centre

41、for Dis-ease Prevention and Control,Solna,Sweden),Mauro Orsini(Ministry of Health,Chile),Marie De Perio(the United States Centers for Disease Control and Prevention,Atlanta,USA),Nicola Petrosillo(Fondazione Policlinico Universitario Campus Bio-Medico,Rome,Italy),Maximil-ian Riess(European Centre for

42、 Disease Prevention and Control,Solna,Sweden),Mark Sobsey(University of North Carolina,USA),Paul Anantharajah Tambyah(National University of Sin-gapore,Singapore),Deborah Yokoe(University of California San Francisco,San Francisco,USA),End TB Transmission Initiative,the TB and Airborne IPC Working Gr

43、oup of Stop TB Partnership,and others who provided input via general feedback mechanisms arranged by the many key stakeholder groups.Other WHO technical departmentsThe following WHO departments provided inputs to the consultation(In alphabetical order of last name):Benedetta Allegranzi(Infection Pre

44、vention and Control),April Baller(Infection Prevention and Control),Sylvie Briand(Epidemic&Pandemic Preparedness and Prevention),Natasha Crowcroft(Immunization,Vaccines and Biologicals),Miranda Deeves(Integrated Health Services),Janet Diaz(Health Care Readiness),Rudi Eggers(Integrated Health Service

45、s),Nedret Emiroglu(Country Readiness Strengthening),Dennis Falzon(Global Tuberculosis Pro-gramme),Daniel Feikin(Universal Health Coverage),Luca Fontana(Strategic Health Opera-tions),Nathan Paul Ford(Global HIV,Hepatitis and STIs Programmes),Ana Lorena Guerrero Torres(Alliance for Health Policy and S

46、ystems Research),Aspen Hammond(Global Influenza Programme),Iman Heweidy(Antimicrobial Resistance and Infection control,WHO Regional Office for the Eastern Mediterranean),Teresa Kasaeva(Global Tuberculosis Programme),Mad-ison Moon(Health Care Readiness),Maria Purificacion Neira(Environment,Climate Ch

47、ange and Health),Kate OBrien(Immunization,Vaccines and Biologicals),Ana Paula Coutinho Rehs(Infectious Hazard Management,WHO Regional Office for Europe),Magdi Samaan(Global Influenza Programme),Alice Simniceanu(Emerging Diseases&Zoonoses),Victoria Willet(Health Care Readiness),Wenqing Zhang(Global I

48、nfluenza Programme),Matteo Zignol(Global Tuberculosis Programme).Financial contributorsAll donors who supported the COVID-19 response enabled this work to be undertaken.xiTerminology used to describe the transmission of pathogens through the air varies across scien-tific disciplines,organizations an

49、d the general public.While this has been the case for decades,during the coronavirus disease(COVID-19)pandemic,the terms airborne,airborne trans-mission and aerosol transmission were used in different ways by stakeholders in different sci-entific disciplines,which may have contributed to misleading

50、information and confusion about how pathogens are transmitted in human populations.This global technical consultation report brings together viewpoints from experts spanning a range of disciplines with the key objective of seeking consensus regarding the terminology used to describe the transmission

51、 of pathogens through the air that can potentially cause infec-tion in humans.This consultation aimed to identify terminology that could be understood and accepted by different technical disciplines.The agreed process was to develop a consensus document that could be endorsed by global agencies and

52、entities.Despite the complex discussions and chal-lenges,significant progress was made during the consultation process,particularly the consen-sus on a set of descriptors to describe how pathogens are transmitted through the air and the related modes of transmission.WHO recognizes the important area

53、s where consensus was not achieved and will continue to address these areas in follow-up consultations.The scope of what type of pathogens were covered in this consultation and the resulting descriptors used in this document are as follows:Pathogens,contained within a particle(known as infectious pa

54、rticles),that travelthrough the air,when these infectious particles are carried by expired airflow(theyare known as infectious respiratory particles or IRPs),and which enter the humanrespiratory tract(or are deposited on the mucosa of the mouth,nose or eye of anotherperson)and;Pathogens from any sou

55、rce(including human,animal,environment),that causepredominantly respiratory infections(e.g.,Tuberculosis TB,influenza,severe acuterespiratory syndrome SARS,Middle East respiratory syndrome MERS),but aswell as those causing infections involving the respiratory and other organ systems(e.g.COVID-19,mea

56、sles).Executive summaryxiiThe following descriptors and stages have been defined by this extensively discussed consultation to characterize the transmission of pathogens through the air(under typical circumstances):Individuals infected with a pathogen,during the infectious stage of the disease(theso

57、urce),can generate particles containing the pathogen,along with water and res-piratory secretions.Such particles are herein described as potentially infectiousparticles.These potentially infectious particles are carried by expired airflow,exit the infec-tious persons mouth/nose through breathing,tal

58、king,singing,spitting,coughing orsneezing and enter the surrounding air.From this point,these particles are known asinfectious respiratory particles or IRPs.IRPs exist in a wide range of sizes(from sub-microns to millimetres in diameter).The emitted IRPs are exhaled as a puff cloud(travelling first

59、independently from aircurrents and then dispersed and diluted further by background air movement in theroom).IRPs exist on a continuous spectrum of sizes,and no single cut off points should beapplied to distinguish smaller from larger particles,this allows to move away fromthe dichotomy of previous

60、terms known as aerosols(generally smaller particles)anddroplets(generally larger particles).Many environmental factors influence the way IRPs travel through air,such as ambi-ent air temperature,velocity,humidity,sunlight(ultraviolet radiation),airflow distri-bution within a space,and many other fact

61、ors,and whether they retain viability andinfectivity upon reaching other individuals.The descriptor through the air can be used in a general way to characterize an infectious dis-ease where the main mode of transmission involves the pathogen travelling through or being suspended in the air.This has

62、similarity with other public health descriptors of infectious dis-eases,such as waterborne and bloodborne,that refer to the main medium through which a specific disease is transmitted,and as commonly understood by the scientific,clinical,public health communities and the general public.The descripto

63、r transmission through the air can be used to describe the mode of trans-mission of IRPs through the air.Under the umbrella of the through the air,two descriptors can be used:Airborne transmission/inhalation:Occurs when IRPs expelled into the air asdescribed above and enter,through inhalation,the re

64、spiratory tract of anotherperson and may potentially cause infection.This form of transmission can occurwhen the IRPs have travelled either short or long distances from the infectiousperson.The portal of entry of an IRP with respiratory tract tissue during airbornetransmission can theoretically occu

65、r at any point along the human respiratory tract,but preferred sites of entry may be pathogen specific.It should be noted that the dis-tance travelled depends on multiple factors including particle size,mode of expul-sion and environmental conditions(such as airflow,humidity,temperature,setting,vent

66、ilation).Direct deposition:Occurs when IRPs expelled into the air following a short-rangesemi-ballistic trajectory,then directly deposited on the exposed facial mucosal sur-faces(mouth,nose or eyes)of another person,thus,enter the human respiratory tractvia these portals and potentially cause infect

67、ion.Global technical consultation report on proposed terminology for pathogens that transmit through the airxiiiExecutive summaryPathogens that can be transmitted to another human via contact transmission(direct contact)and not via transmission through the air(e.g.via hands)or indirectly via touchin

68、g secondary objects(fomites e.g.tabletops),or that enter the human body via routes(e.g.open wounds,sharps or needle-stick injuries)or pathogens with an environmental reservoir with a predilec-tion for lungs(e.g.,Legionella and melioidosis)are not covered by the included descriptors but are reference

69、d for completeness.This consultation is the first phase of the global scientific debate led by WHO.From which the next steps will require further technical and multidisciplinary research and exploration of the wider implications of the updated descriptors before any update on infection prevention an

70、d control or other mitigation measures guidance is issued by WHO.1Understanding the modes of transmission for any pathogen is essential for developing and adapting effective and appropriate public health,clinical,infection prevention and control measures to prevent infections and mitigate the spread

71、 of that pathogen.Key public health and social measures include implementing multiple approaches,such as:case finding;separation and/or isolation;contact tracing and supported quarantine;robust testing;physical distancing;hand hygiene,mask-wearing;delivery of prompt and appropriate treatments;enviro

72、nmental cleaning and disinfection;ensuring adequate ventilation;infection prevention and control measures in health care settings;clinical case management.All these measures are influenced by an understanding of how,where and when transmission of a pathogen occurs and are implemented in a variety of

73、 different settings,including for health care workers and other occupations in health care settings,usually using a hierarchy of con-trols approach.The way pathogens are transmitted is complex and depends on many factors and may be classified in different ways.The modes of transmission follow classi

74、c epidemiological principles and refer to how an infectious agent,which can be pathogenic,can be transferred to another person,object,the environment,water,food,insect or animal.In this sense,transmission could simply be classified through the various media the infectious pathogens use to move betwe

75、en the source and susceptible recipient e.g.bloodborne,waterborne,vector-borne,airborne and through the air(13).How to measure and quantify the predominant mode of transmission for different pathogens that are transmitted through the air remains challenging,particularly for newly emerging pathogens.

76、One current major issue contributing to this challenge is that the terminology used to describe the transmission of pathogens through the air varies significantly across scientific dis-CHAPTER 1Introduction2ciplines,organizations and the general public(4).While this issue has been known for many yea

77、rs(420),it was brought to the forefront during the COVID-19 pandemic when intensive global communications were needed.During the pandemic,the terms airborne,airborne transmission,droplets and aerosols were used in different ways,by different stakeholders,which contributed to confusion in communicati

78、ng how this pathogen was transmitted in human populations via air(21).Hence,a lack of consensus on what exactly is meant by air-borne,airborne transmission has highlighted the need for better alignment of these terms across disciplines,agencies and pathogens.In 2020,the WHO COVID-19 leadership team

79、consulted with other major public health agencies and agreed on the need to reassess the use of terminology relating to transmission of pathogens through the air.As a starting point,and in order to ascertain whether significant and unresolved variation in the definitions existed between different sc

80、ientific disciplines,the WHO Health Emergencies Programme,together with the Science Divisions Rapid Review Group,conducted a scoping literature review of the existing definitions of airborne transmission of pathogens in 2021.This review(manuscript under preparation)found considerable variation in th

81、e scope of the term airborne transmission,including differences in particle size limits,duration in the air,distance travelled,method of dispersal and other properties.In November 2021,WHO began the process of convening a global technical consultation with the aim to resolve inconsistencies in termi

82、nology and seek agreement regarding descrip-tors and terminology relating to the transmission of pathogens through the air.This consul-tation report summarizes the areas of consensus reached from the expert discussions on the proposed terminology and descriptors to be used.Global technical consultat

83、ion report on proposed terminology for pathogens that transmit through the air3The key objectives of this global technical consultation process were:to bring together global experts of various disciplines including(but not limited to)experts in epidemiology,microbiology,clinical management,infection

84、 preven-tion and control,bioengineering,physics,air pollution,aerosol science,aerobiology,public health and social measures,and social science;and to share knowledge and seek a consensus regarding generic terminology and descrip-tors used to describe the transmission of pathogens through the air tha

85、t can poten-tially cause infection in humans.The aim of the consultation was to:identify a language for these terms that can be understood,accepted and eventually implemented by all disciplines and experts globally.The scope of pathogens covered in this consultation and the resulting descriptors con

86、tained in this document are as follows:Pathogens,contained within a particle(known as infectious particles),that travel through the air and these infectious particles are carried by expired airflow(now known as infectious respiratory particles or IRPs),which enter the human res-piratory tract(or are

87、 deposited on the mucosa of the mouth,nose or eye of another person);Pathogens from any source(including human,animal,environment),that cause pre-dominantly respiratory(e.g.,TB,influenza,SARS,MERS)but also those pathogens causing infections involving the respiratory and other organ systems(e.g.COVID

88、-19,measles).To note:Pathogens that are transmitted to another human via contact transmission(direct contact),not via transmission through the air(e.g.via hands)or indirectly via touching secondary objects(fomites e.g.tabletops),or that enter the human body via routes(e.g.via the skin or open wounds

89、,via sharps or needle-stick injuries)or path-ogens with an environmental reservoir with a predilection for lungs(e.g.,Legionella CHAPTER 2Objectives,aim and scope4and melioidosis)are not covered by the included descriptors but are referenced for completeness;For simplicity,the descriptors,figures,ta

90、bles and other text included in this doc-ument usually refer to humans only(e.g.person/individual rather than the more generic term source,which could be used to refer to environmentally derived patho-gens)and focus on transmission from,and to,the respiratory tract of humans,rather than other ports

91、of entry(e.g.via skin or open wounds);Detailed descriptions of all possible transmission factors,for every known pathogen,in all possible settings,were not included in this consultation.Global technical consultation report on proposed terminology for pathogens that transmit through the air5Details o

92、f the governance structure and formation of the Technical Consultation Group(TCG)can be found in Annex 1.This global technical consultation used a staged approach(see Annex 2),with two complementary methods(see Annex 3).This was a multi-agency,multidisciplinary initiative,including 41 technical expe

93、rts and the WHO Secretariat(see Annex 4)selected to provide expert evidence and to contribute to open discussions via virtual meetings and submit written comments following each draft of the resulting document(s).The members of the full TCG were included based on their technical expertise,and to ens

94、ure appropriate gender and geographical balance.Invitations to join the TCG of experts were approved and issued by the WHO Chief Scientist.All consulted experts were assessed for conflicts of interest and asked to sign confidentiality agreements,per normal WHO procedures.None of the experts reported

95、 any conflict considered relevant.Given the high likelihood of substantive disagreement among the diverse selected experts,all were encouraged to provide full,frank but respectful contribu-tions to the consultation discussions via their verbal contributions and written feedback,but to aim for overal

96、l descriptors that multiple agencies could co-endorse and adopt.This technical consultation process was not that of a formally constituted WHO TCG,and thus,formal recommendations were not an expected output of the process.As such,compre-hensive systematic evidence reviews pertaining to every known p

97、athogen were not undertaken.Instead,the process aimed to be a starting point for what is anticipated to be difficult and complicated discussions on a topic with enormous complexity,which would form the basis for common language across disciplines.However,it would likely require further work in order

98、 to operationalize and implement within pathogen-,discipline-and setting-specific contexts.Comments provided during virtual meetings and via written feedback covered an extremely wide range of areas relating to the topic.This included mechanisms,modes,settings,pathogen specific characteristics,epide

99、miological factors,source control,host and many other factors relating to the transmission of IRPs.An informal approach,with unstructured discussion,was used for this consultation,as this can enable better articulation of views and opinions rather than using more structured approaches(such as the De

100、lphi method,surveys or formal voting).The possibility of having strongly dissenting views recorded was offered to members of the TCG.The term consensus has been used in this document to convey a process whereby these group decision-making methods were employed in the consultation to achieve the resu

101、lting document.CHAPTER 3Methods and processes7The lengthy consultation process confirmed how extremely complex and sensitive it is to address the objective laid out in this global technical consultation.As anticipated,it was challenging to achieve consensus on all aspects of this topic where experts

102、 had mutually exclusive and dia-metrically opposed positions regarding the supporting science,some of which still remain,and are summarized in Annex 5.Despite these hurdles,progress was made to reach a consensus of the overarching termi-nology of transmission through the air with sub-categories of a

103、irborne transmission”and direct deposition.Importantly,it was agreed by the TCG that Figure 1 is a schematic depic-tion of current understanding on how pathogens are transmitted through the air,although not all organisms employ all the routes shown.There remains some disagreement regarding some of t

104、he chosen labels and terminology to describe the schematic(see Annex 5 for discussion points).To articulate the schematic depiction of Figure 1 in words,the following descriptors are proposed to be used to characterize the transmission of pathogens through the air,under usual circumstances.Figure 1.

105、Potential modes of transmission of infectious respiratory particlesCHAPTER 4OutcomesSource:Developed by A.Manna and L.Bourouiba,adapted from(8,12,22,23).8Table 1.Features of infectious respiratory particles and descriptors for modes of transmissionMode of transmissionTypical distance from the source

106、Route of transfer to another humanRespiratory tract entry mechanismRespiratory tract entry portalSchematic depictionTHROUGH THE AIRAirborne transmission/inhalationAny distanceThrough the air(suspended in air or moving via air flows)InhalationAnywhere along the respiratory tractDirect depositionShort

107、Through the air(semi-ballistic trajectory)Deposition on the mucosa Mouth,nose or eyes*CONTACT#Direct contact ShortNot through the airDirect transfer(via touch,usually with hands)Mouth,nose or eyes*Indirect contactAny distanceNot through the air,although IRPs may reach an intermediate object through

108、the airIndirect transfer(via touching an intermediate object)Mouth,nose or eyes*Note that the mucosa of the eyes is not part of the human respiratory tract but are a portal of entry into the respiratory system.#Note that this mode of transmission to another human does not involve a through the air r

109、oute but is included here for completeness.Depictions above assume the human(s)on the left is/are the infectious person(s)and the human on the right is the recipient of the IRP.Note that touch is not through the air transmission but included for completeness and it does not include sharp injuries li

110、ke needle prick.Source of figures:A.Manna and L.Bourouiba.Based on(8,12,23).3.1 Modes of transmission The mode of transmission(Table 1)includes the formation,release,transport and biophysical/biochemical changes to IRPs that occur when they move away from an infectious individual and travel towards

111、another individual.In addition,IRPs may directly deposit on the mouth,nose or eye of another individual,and can potentially infect the individual.Global technical consultation report on proposed terminology for pathogens that transmit through the air9Chapter 4 OutcomesDuring the infectious stage of

112、the disease,an infected person can generate particles containing the pathogen,along with water and respiratory secretions.Such particles are here described as infectious respiratory particles or IRPs(2436).These IRPs are then carried by expired airflow,exit the infectious persons mouth and/or nose w

113、hen they breathe,talk,sing,spit,cough or sneeze and are released into the surrounding air.The IRPs exist in a wide range of sizes(from sub-microns to millimetres in diameter)(22,25,32,3755)and travel in the air in a turbulent puff cloud(exhaled mixture of gases from the lungs and respiratory particl

114、es)(8,23).The IRPs are carried by the puff cloud and remain concentrated until the cloud reduces sufficiently in momentum to enable IRP dispersal by the background air movement.There are many factors that can influence the particle distribution,spread and subsequent effect on an individual of exhale

115、d IRPs(depicted in Figure 1):Host:Immune status of the host,including prior infection,vaccination,status of anindividuals innate,cellular and humoral immunity;Pathogen characteristics:The ability of the pathogen to remain infective aftersuspension in the air and the dose-infection relationship for t

116、he pathogen after itdeposits on a surface in the hosts respiratory tract;Particle size:IRPs are formed with a continuous spectrum of aerodynamic sizes,and no single cut off points should be applied to distinguish smaller from largerparticles,this allows to move away from the dichotomy of what have p

117、reviously beenknown as aerosols(generally smaller particles)and droplets(generally larger par-ticles)(8,12,56,57).Nonetheless,there are usually more numerous smaller,com-pared to larger,particles;Speed of expulsion:The speed of expulsion can vary depending on the force ofexpiration and other factors

118、 relating to the surrounding conditions(8,12,14,23,55,5867).Because of dilution,the concentration of IRPs is higher closer to the source(where the IRPs exit the infectious persons respiratory tract)and become less con-centrated as they disperse randomly further away from the source;Influence of grav

119、ity:Under the influence of gravity,after being expelled,larger IRPsrapidly fall,eventually reaching the ground or another surface,usually within 1-2metres of where they were emitted from the infectious persons respiratory tract(13,68,69);Mode of expulsion:Activities resulting in more forceful expira

120、tion(i.e.,larger totalmomentum),such as sneezing,coughing,loud singing and shouting,are known topropel IRPs further than 1-2 metres(8,12,23);Evaporation:Following emission from the mouth and/or nose,IRPs of all sizesundergo evaporation of some of their water content.IRPs decrease in size andweight a

121、t various rates in a common environment.Evaporation rate has an impacton how long particles remain in the air and how far they may be transferred beforesettling on a surface.The smaller the particle,the longer it is likely to remain in theair,and the further it is likely to travel;Environmental cond

122、itions:In addition to the above factors for transmission,theambient air temperature,sunlight,humidity,airflow and size,occupancy and use ofthe space where IRPs are expelled impact the infectivity,duration,speed of trans-mission and distance travelled of IRPs(2325,29,33,48,54,55,62,66,7087);Concentra

123、tion of IRPs:With increasing distance from the source,dilution withambient air increases and concentrations of IRPs decrease.Concentrations are alsoaffected by ambient airflows from ventilation systems.Concentrations can increaseover time if ventilation is inadequate(8890).10After IRPs are emitted f

124、rom an infectious person,they progressively diminish in infectivity over a time frame specific to the pathogen,either due to decrease in an organisms infectivity with time or more dispersion and dilution leading to lower concentrations of particles in the air at any given position.The modes in which

125、 IRPs then travel to,enter,and can potentially infect another individual can broadly be described as occurring in the following three ways(depicted in Figure 1 and Table 1):1.i)Airborne transmission/inhalation:Occurs when IRPs expelled into the air(as described above)and enter,through inhalation,the

126、 respiratory tract of another person.This form of transmission can occur when the IRPs have travelled either short or long distances from the infectious person(28,37,41,43,53,63,84,9196).The portal of entry of an IRP with respiratory tract tissue during airborne transmission can theoretically occur

127、at any point along the human respiratory tract,but preferred sites of entry may be pathogen specific.It should be noted that the distance travelled may depend on multiple factors including particle size,mode of expulsion and environmental conditions(such as airflow,humidity,temperature,setting,venti

128、lation,etc.).2.ii)Direct deposition:Occurs when IRPs are expelled into the air following a short-range semi-ballistic trajectory,then are directly deposited on the exposed facial mucosal sur-faces(mouth,nose or eyes)of another person,thus,entering the human respiratory tract via these portals and po

129、tentially causing infection(38,41,42,47,48,5254,58,62,67,72,76,84,95,97106).3.iii)Contact transmission(added for completeness):Contaminated surfaces are created when IRPs expelled into the air settle on a surface,or when an infected person transfers infectious respiratory secretions by firstly touch

130、ing their own mouth,nose or eyes and then touching a surface or shaking hands(25,34,42,48,54,58,72,84,97,98,107,108).Infectious pathogens on the contaminated surfaces are then transferred to another person who touches that contaminated surface and then their own mouth,nose or eyes.This is commonly k

131、nown as indirect contact transmission.In addition,direct contact transmis-sion can occur when an infectious person directly transfers infectious pathogens from their own respiratory tract,not via IRPs,to another person by being in direct contact with that person(e.g.via a handshake),who then directl

132、y transfers the IRPs into their own mouth,nose or eyes.This form of transmission does not directly involve the trans-mission of pathogens to humans through the air,so is not considered part of the through the air descriptors covered by this document,but is included here for completeness(see also Fig

133、ure 1,Table 1).3.2 The term through the air transmissionThe descriptor through the air can be used in an overarching way to characterize an infectious disease where transmission involves the pathogen travelling through or being suspended in the air.This has similarity with other public health descri

134、ptors of infectious diseases,such as water-borne and bloodborne,which refer to the main medium through which a specific disease is transmitted and is commonly understood by the general public.However,the medium alone does not address the factors of time and distance over which the air remains infect

135、ious,and those modifiers will be necessary for the phrase to be useful for public health implementation,which needs to be part of future research.The phrase transmission through the air can be used to describe the transmission of IRPs through the air,via either airborne transmission/inhalation or di

136、rect deposition modes(or Global technical consultation report on proposed terminology for pathogens that transmit through the air11other labels matching equivalent descriptions)as outlined above.This can therefore include the transmission of IRPs on a spectrum of sizes,over both short and long dista

137、nces.See Figure 1 and Table 1 for schematic descriptions of these modes of transmission(and other related trans-mission modes for completeness).3.3 Exposure and its relationship to infection Exposure of pathogens through the air is a physical phenomenon in which pathogens released from the respirato

138、ry tract of an infectious person end up in the respiratory tract of another.Exposure does not guarantee successful infection of the susceptible host,as infection is an event that can only occur after the expelled IRPs enter the respiratory tract,come into contact with the respiratory tissues,followe

139、d by multiplication of the infectious pathogens within a susceptible person thus,the full chain of events and conditions that comprises transmission.There are a multitude of complex factors that influence whether a susceptible person becomes infected,including biological characteristics of the patho

140、gen and the particles it is contained within,immune responses in the susceptible host,concentration of microbes in the IRP,dura-tion of exposure and environmental factors.This document does not provide detailed informa-tion on these complex factors that can ultimately result in infection.3.4 Some fa

141、ctors affecting through the air transmission of IRPs and infection riskAs mentioned,many factors can affect the viability,infectivity and virulence,and concentration of expelled IRPs and contribute to the risk of infection and disease in another person.Numerous mitigation measures can reduce the ris

142、k of pathogens that transmit through the air;distancing,masking,adequate ventilation/dilution and airflow pattern within indoor spaces should be considered to help mitigate the risk of airborne transmission of IRPs.This is because the transmission of IRPs is more likely to occur indoors than outdoor

143、s because the opportunity for dilution of IRPs in the surrounding air is almost always greater outdoors.An example of recent initiatives aiming to estimate the risk of airborne transmission indoors is the Indoor Airborne Risk Assessment in the context of SARS-CoV-2(109).This risk assessment tool use

144、s detailed relevant components,including:the emission rate(number/volume of IRPs exhaled by an infectious person in a given time)(41,52,75,77,87);the removal rate(total number/volume of IRPs removed from the air in a given time by ventilation or deposition or inactivation)(42,60,63,77,84,110,111);Ex

145、posure(difference/balance between the emission rate and the removal rate and the exposure time)(35,44,81,110,112115,48,50,54,60,63,65,71,76);the administered dose(dose of IRPs which are actually retained and to which another person is exposed)(25,41,48,50,59,6265,7175,77,80,81,83,111113,116119);the

146、resulting probability and risk of infection(taking into account the administered dose,the exposed persons susceptibility to infection,severity of the resulting disease,the pathogen specific transmissibility characteristics,and other risk and host factors)(41,108,120125).Detailed descriptions of the

147、interplay between these complex factors for specific pathogens,in specific settings,are not within the scope of this document.Chapter 4 Outcomes12It is important to note that different pathogens will have different predominant,or mixed,modes of transmission,including through the air transmission,whi

148、ch require detailed discus-sions with relevant expert groups to determine appropriate mitigation strategies.In addition to mode of transmission,these discussions will include the epidemiologic and virologic char-acteristics of the pathogens,the degree or severity of illness caused,the impact and bur

149、den on health care systems,and other factors,thus transmission pathways alone are not sufficient to indicate which mitigation strategies are chosen.The development of evidence-based guidance,transmission prevention and mitigation measures will need to be tailored differently for dif-ferent pathogens

150、 via different routes and in different settings.In addition,pathogens vary in their virulence,treatability,frequency and potential impact on different hosts in different set-tings.Hence,pathogen-and setting-specific guidance regarding mitigation measures,includ-ing infection,prevention and control(I

151、PC)guidance,is needed,but is not within the scope of this document.3.5 Immediate practical implicationsThe updated terminology no longer includes a cut off of particle size,but rather a continuum of particle sizes of IRPs.These will have practical implications for various technical disciplines.For e

152、xample,in IPC,the goal is to prevent and/control microbial transmission.Control includes both limiting the spread of infection and limiting the morbidity and mortality resulting from infection.To prevent or limit the spread of infection,exposure must be addressed,prioritizing interventions according

153、 to the severity of the resulting diseases.This means that for the same transmission mode,different prevention and control measures may be selected,depending on factors relating to the infectious agent,source,environment and host.There must be a clear understanding that when describing transmission

154、of pathogens,this must work backwards from factors affecting infection risk,not just forwards from source generation and infectious particle characteristics,such as their concentrations,size and aerobiological properties.There is NO suggestion from this consultative process that to mitigate the risk

155、 of short-range airborne transmission full airborne precautions1(as they are currently known)should be used in all settings,for all pathogens,and by persons with any infection and disease risk levels where this mode of transmission is known or suspected(126).But conversely,some sit-uations will requ

156、ire airborne precautions.This would clearly be inappropriate within a risk-based infection prevention approach where the balance of risks,including disease incidence,severity,individual and population immunity and many other factors,need to be considered,inclusive of legal,logistic,operational and f

157、inancial consequences that have global implications regarding equity and access.Additionally,the new term of direct deposition is akin to the existing droplet transmis-sion mode,but without any specific particle size designation.While further understanding of this form of transmission is elucidated,

158、for pathogens suspected or known to transmit via this mode,the existing droplet precautions should continue to be used to prevent direct deposition of respiratory particles,but personnel may still be vulnerable to infection via airborne transmis-sion/inhalation if the pathogen can also transmit via

159、this mode.Similarly,for transmission via contact mode,existing precautions known as contact precautions should continue to be used.Global technical consultation report on proposed terminology for pathogens that transmit through the air 1 Such as patient placement in an airborne infection isolation r

160、oom,appropriate personal protective equipment(PPE)use by health care workers(including a respirator),limited transport and movement of patients,and asking the patient to wear a mask when appropriate.13Most importantly,while discussions during the consultation were based on the available best science

161、,it was agreed it was important to balance scientific insights with availability,access,affordability and other practical realities to minimize health inequity and avoid potential con-sequences such as the ability to access PPE.The implementation of the terminology on transmission through the air an

162、d all other modes of transmission will require further empirical multidisciplinary research and an evi-dence-based review process.Terminology of the modes of transmission may have ramifica-tions on current measures and recommendations in health care settings,as well as in others including,but not li

163、mited to,educational settings,transport and workplaces.Many diverse disciplines will need to be bought together to consider the implications for specific pathogens,for nonspecific infection control measures,such as good hygiene practices,and when the modes of transmission are not known at the time.3

164、.6 Key research gaps and next steps Physical science studies have emphasized the importance of understanding the movement of particles through the air in order to design potential interventions to lower the risk of infec-tion.However,studies that measure infection and the impact of mitigation interv

165、entions for specific pathogens are challenging as the ability to design and conduct clinical trials,or other study types,is highly affected by the enormous heterogeneity of factors regarding the patho-gens themselves(and their characteristics),the settings where pathogens are transmitted,and the ind

166、ividuals who eventually become infected by them.Well-designed research studies are needed to inform mitigation strategies.Guidance for infection prevention depends on a wide range of factors that need to be con-sidered by health care experts and scientists particularly in emergent situations.However

167、,there remains a clear and urgent need for the design and conduct of further interdisciplinary research to build robust evidence regarding transmission mechanisms and infection preven-tion measures and strategies.Future research should include animal models,human challenge experiments,as well as oth

168、er observational and interventional study designs.An important next step is to consider how the definitions described here will be applied to wider evidence base and risk assessment processes,to inform wider IPC and clinical research,epidemiology evidence base and future IPC measures as well as for

169、engineering,physics research and aerosol science.Behavioural research is important for implementing acceptance,adoption and action of IPC and public health measures.Chapter 4 Outcomes15This global technical consultation process was a concerted effort of many influential and expe-rienced experts.Desp

170、ite the challenges faced to arrive at some degree of consensus on such sensitive issues and terminology,progress was made.WHO recognizes the concerns and the non-agreed aspects raised and will continue to address these in future work.Reaching consensus on the term infectious respiratory particles,mo

171、ving away from a strict dichotomy of particle sizes,and accepting that smaller IRPs can be transmitted at both short-and long-range depending on several influencing factors,are all major achievements.Consid-eration for the use of the phrase transmission through the air as an umbrella term to describ

172、e the transmission of IRPs through the air via either airborne transmission or direct deposition modes simplifies a highly complex issue but will require specific socialization and training to be understood by health care workers and the general public.Such a shift in the use of this terminology in

173、this way is not without its consequences.Hence,the descriptors included in this document should be seen as a starting point for further evidence review,urgent and detailed discussions and,multidisciplinary research with associ-ated funding to address pathogen-,discipline-and/or setting-specific impl

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260、,the WHO Chief Scientist,was the Convening Lead for this tech-nical consultation until her departure from WHO in December 2022,after which,this role was assumed by the acting Chief Scientist,Dr John Reeder,then from 8May2023,by the new incoming Chief Scientist,Dr Jeremy Farrar.The Chief Scientist wa

261、s supported by a WHO Sec-retariat who operationalized the project.A project Working Group(WG)was convened,consisting of 10 representatives from key agencies including the United States CDC,Africa Centres for Disease Control and Prevention,European Centre for Disease Prevention and Control,China CDC,

262、and selected highly cited experts on this topic from academic institutions.Representatives from the key agencies listed above were nominated by the agencies themselves,at the request of the WHO Chief Scientist.The criteria for selecting experts who were highly cited was based on the most cited autho

263、rs in a scoping literature review of the existing definitions of airborne transmission of pathogens in 2021(see Introduction),but also with consideration for geographical and gender balance within the WG.This core group was considered a starting point for identifying other relevant global experts wh

264、o were currently active in this area due to the COVID-19 pandemic.The WHO Secretariat proposed a WG Chair(Gagandeep Kang)and Co-Chair(Yuguo Li)who were selected from the WG members,with confirmation of election by the WG.The remit of the WG was to drive the consultation process,ensure the required d

265、iversity of viewpoints were included(e.g.by suggesting names for the full global TCG),and to assist the Convening Lead in reaching consensus to produce the final document.The list of members,their affiliations and areas of expertise,who were involved in each part of the consultation process are incl

266、uded in Annex 4.Annexes26Annex 2.Steps in the technical consultation processWHO starts the global technical consultation WHO asks DOI forms from invited experts 2ndWG meeting 2nd TCG meeting 4th TCG meeting Nov.2021 31 Mar.2022 21 Apr.2022 12 May 2022 10 June 2022 16 June 2022 11 Nov.2022 27-28 Apr.

267、20224 Aug.2023 16 Nov.2023 I WHO invites CDC Directors&other experts suggested by WHO technical departments I lstWG meeting I lstTCG meeting 31/10/2022 Chief Scientist sent updates to CDC Directors I 3rd TCG meeting(Hybrid)including guest discussants 22/6/2023 Chief Scientist sent updates to CDC Dir

268、ectors.I WHO shared the final draft of the consultation report 13/9/2023 Chief Scientist sent updates to CDC Directors 24/11/2023 Chief Scientist sent updates to CDC Directors T Received agreements from all 4 CDCs Directors WG=Working GroupTCG=Technical Consultation GroupDOI=Declaration of InterestG

269、lobal technical consultation report on proposed terminology for pathogens that transmit through the air27AnnexesAnnex 3.Two processes undertaken for the consultation processStage 1:Based on the results of the scoping literature review of the existing definitions of air-borne transmission(see Introdu

270、ction section),and an initial internal consultation,the WHO Secretariat developed a Concept Note and a discussion document with a matrix of the:list of key questions(or domains)that needed consensus(i.e.,where major disagree-ment existed);major differing viewpoints within each of those questions;and

271、list of the potential(different)actionable ways to resolve those questions.The WG members were selected by the WHO Secretariat(using the criteria outlined in the Governance section in Annex 1)and were sent the Concept Note with an email inviting par-ticipation.Two WG meetings were held virtually on

272、12May2022 and 10June2022 to collect considered inputs into the first discussion document and suggested members for the wider,full TCG(see Stage 2 below).In attendance at these meetings were ten members of the WG,the WHO Chief Scientist,and the WHO Secretariat(see Annex 4).Stage 2:The WHO Secretariat

273、 convened the full TCG,as follows:The full TCG consisted of the WG Chair,Co-Chair,the WG members plus additionalkey,selected stakeholders/agencies,with wide multidisciplinary representation(seeAnnex 4);Input was sought from this group via informal,but structured,targeted ways e.g.,byinviting detaile

274、d written comments on the discussion documents,and at three vir-tual meetings to verbally exchange views and debate unresolved issues;TCG members were encouraged to share and discuss draft documents with theirrelevant constituencies and collect,collate and provide written feedback to the WHOSecretar

275、iat.The first virtual meeting of the full TCG took place on 17June2022 and was followedby an opportunity to provide written feedback on a first draft document;This,and all subsequent,drafts were prepared by the WHO Secretariat and approvedby the TCG Chair and Co-Chair prior to distribution for feedb

276、ack;A total of 41 technical experts were consulted(see Annex 4).Thirty-one experts pro-vided written feedback and a further eight individuals provided verbal-only input viatheir contributions at the virtual meetings.Four experts were invited to contributeand accepted but did not provide either verba

277、l or written input;Following these consultations,the WHO Secretariat,with assistance from the WGChair and Co-Chair,revised the draft document and circulated it to the full TCGon 23October2022,with a deadline for feedback of 7November2022.The feedbackprovided by the TCG to that point in time was shar

278、ed with members of the group on27October2022;A second virtual meeting of the TCG was held on 11November2022 at whichremaining unresolved issues were discussed and dissenting views were noted;A revised version of the document was circulated to the TCG on 19December2022.TCG members were asked to seek

279、and return further consolidated feedback fromtheir respective constituencies by 31January2023;In response to this version of the document,523 individual comments were receivedby the WHO Secretariat.This large amount of detailed input was collated and sum-28marized during February-March 2023.A revise

280、d version was drafted and made ready for circulation in mid-April 2023;At the request of the WHO Director-General,a hybrid third TCG meeting(inGeneva and online)was held over two days on 27-28April2023.All TCG membersand the relevant WHO technical leads were invited to attend,along with severaladdit

281、ional commentators who had previously expressed views on the topic.34 TCGmembers,31 WHO staff and 23 additional commentators were able to attend at leastsome parts of this hybrid meeting;A revised version was drafted in response to these inputs and was sent to the TCGmembers for inputs on 16June2023

282、,with a request for inputs by 7July2023;A final,virtual,fourth meeting of the TCG was convened on 4th August 2023 whereany remaining input was received and discussed;The revised version was shared on 8th September and the final version on 16th Novem-ber 2023;Discussions with the relevant agencies re

283、garding endorsement and publication wasthen undertaken and the final document was published in April 2024.As with the development of many other WHO normative products,the decision-making pro-cess used for this consultation was to aim for consensus among the contributing experts.As per the WHO Qualit

284、y Assurance Handbook for normative product development(In publica-tion),the process of reaching consensus in group decision-making always involves discussion and compromise to arrive at a decision that is acceptable to all parties and is a process whereby the consent of all group members is pursued.

285、When consensus is said to have been reached,it generally means that every group member finds the proposed resolution acceptable or at least lends it support,even if less than wholeheartedly.Global technical consultation report on proposed terminology for pathogens that transmit through the air29Anne

286、x 4.Details,affiliations,expertise and roles of participants NoNameSexOrganizationArea of expertise/disciplineCountryRegion*Role1Yewande AlimiFemaleAfrica CDCInfection prevention and controlEthiopiaAFRWG2Yaseen ArabiMaleCollege of Medicine,King Saud Bin Abdulaziz University for Health Sciences,Riyad

287、hIntensive care Saudi ArabiaEMRTCG3Lisa AskieFemaleWorld Health OrganizationEpidemiology,evidenced-based medicineSwitzerlandHeadquartersSecretariat4Abdullah AssiriMaleMinistry of HealthInfectious diseasesSaudi ArabiaEMRWG5Julie BennettFemaleDepartment of Public Health,University of OtagoEpidemiology

288、,infectious diseases,indoor air qualityNew ZealandWPRTCG6Gautam BhanMaleIndian Institute for Human Settlements,BengaluruUrban poverty,housingIndiaSEARTCG7Arnab BhattacharyaMaleTata Institute of Fundamental Research,Mumbai Engineering,physicsIndiaSEARTCG8Gabriel BirgandMaleNantes University Hospital;

289、Regional center for IPC,Pays de la Loire regionInfection prevention and controlFranceEURTCG9Lydia BourouibaFemaleMassachusetts Institute of Technology,CambridgeFluid physics,Infectious disease transmission,and Engineering ScienceUSAAMRTCG10Giorgio BuonannoMaleUniversity of Cassino and Southern Lazio

290、Environmental engineering,Aerosols science,indoor air qualityItalyEURTCG11Cheryl CohenFemaleCentre for Respiratory Disease and Meningitis,National Institute for Communicable DiseasesEpidemiology,influenza,respiratory disease South AfricaAFRTCG12Benjamin CowlingMaleSchool of Public Health,The Univers

291、ity of Hong KongInfectious disease epidemiologyHong Kong SAR,ChinaWPRTCG13Jeremy FarrarMaleWorld Health OrganizationInfectious disease and tropical medicine,clinical scienceSwitzerlandHeadquartersConvening Lead(May 2023-present)14John GroveMaleWorld Health OrganizationPublic health SwitzerlandHeadqu

292、artersSecretariat(Nov 2021Sep 2022)15Ana Lorena Guerrero TorresFemaleWorld Health OrganizationPublic health and Infectious disease,clinical scienceSwitzerlandEURSecretariat16David SC HuiMaleStanley Ho Centre for Emerging Infectious Diseases,The Chinese University of Hong KongRespiratory medicineHong

293、 Kong SAR,ChinaWPRTCG17Gagandeep KangFemaleChristian Medical College,The Wellcome Trust Research Laboratory,Division of Gastrointestinal Sciences,VelloreMicrobiologyIndiaSEARWG Chair18Michael KlompasMaleHarvard Medical School,BostonInfectious diseasesUSAAMRTCG19Nancy LeungFemaleSchool of Public Heal

294、th,The University of Hong KongEpidemiology,respiratory infections and vaccinations,communitybased studiesHong Kong SAR,ChinaWPRTCGAnnexescontinues.30NoNameSexOrganizationArea of expertise/disciplineCountryRegion*Role20Yuguo LiMaleDepartment of Mechanical Engineering,The University of Hong KongBuildi

295、ng environment,environmental engineeringHong Kong SAR,ChinaWPRWG Co-Chair21Li LiuMaleTsinghua University,BeijingAerosol transport,airborne transmissionChinaWPRTCG22Taronna MainesFemaleUnited States CDCMicrobiology,immunology,influenzaUSAAMRWG23Linsey MarrFemaleVirginia TechEnvironmental engineering,

296、aerosol science,airborne transmissionUSAAMRTCG24Donald MiltonMaleInstitute for Applied Environmental Health,University of Maryland School of Public HealthEnvironmental and occupational medicine,aerobiologyUSAAMRTCG25Lidia MorawskaFemaleQueensland University of Technology,Faculty of Science,School of

297、 Earth&Atmospheric SciencesPhysics,engineering,and indoor air qualityAustraliaWPRWG26Shiva NagendraMaleIndian Institute of Technology,MadrasAir quality monitoring,environmental engineeringIndiaSEARTCG27Edward NardellMaleHarvard Medical School,BostonPulmonary medicine,tuberculosisUSAAMRWG28Isabel Och

298、oaFemaleMinistry of Health,PeruBuilding design and engineering approaches to airborne infection controlPeruAMRTCG29Jon OtterMaleHealthcare Associated Infections,Antimicrobial Resistance,Imperial College,LondonHealthcare Associated Infections,Antimicrobial Resistance,clinical scienceUnited KingdomEUR

299、TCG30Malik PeirisMaleSchool of Public Health,The University of Hong Kong Clinical and public health virologyHong Kong SAR,ChinaWPRTCG31Diamantis PlachourasMaleEuropean Centre for Disease Prevention and Control Infection prevention and controlSwedenEURWG32Kevin PoggenpoelMaleSouth Africa Federation o

300、f Healthcare EngineeringHospital engineeringSouth AfricaAFRTCG33Thidar PyoneFemaleWorld Health OrganizationPublic health,health systems and policy,medicineSwitzerlandHeadquartersSecretariat34Hua QianMaleSoutheast University,NanjingBuilding ventilation,engineering control of infectious diseaseChinaWP

301、RTCG35John ReederMaleWorld Health OrganizationInfectious diseases,clinical research,microbiologySwitzerlandHeadquartersConvening Lead(Dec 2022Apr 2023)36Jacqui ReillyFemaleGlasgow Caledonian UniversityInfection prevention and controlUnited Kingdom EURTCG37Chad RoyMaleNational Primate Center,Tulane U

302、niversityInfectious disease aerobiologyUSAAMRTCG38Fatima SerhanFemaleWorld Health OrganizationVirologySwitzerlandHeadquartersSecretariatGlobal technical consultation report on proposed terminology for pathogens that transmit through the air.continuedcontinues.31AnnexesNoNameSexOrganizationArea of ex

303、pertise/disciplineCountryRegion*Role39Soumya SwaminathanFemaleWorld Health OrganizationEpidemiology,tuberculosisSwitzerlandHeadquartersConvening Lead(Nov 2021Nov 2022)40Shin-ichi TanabeMaleDepartment of Architecture,Waseda UniversityArchitecture,human environmental engineeringJapanWPRTCG41Julian W.T

304、angMaleClinical Microbiology,University Hospitals of Leicester NHS Trust&Respiratory Sciences,University of LeicesterInfectious diseases,microbiology,virology,aerobiology,infection controlUnited KingdomEURTCG42Raymond TellierMaleMcGill University,MontrealMedical microbiology,infectious diseases,viro

305、logyCanadaAMRTCG43Kwok Wai ThamMaleNational University of Singapore,SingaporeAirborne transmission and infection control,indoor air qualitySingaporeWPRTCG44Maria van KerkhoveFemaleWorld Health OrganizationInfectious disease epidemiologySwitzerlandHeadquartersSecretariat45Richard WebbyMaleSt Jude Chi

306、ldrens Research Hospital,MemphisInfectious diseases,virologyUSAAMRWG46Dongqun XuFemaleNational Institute of Environmental Health,China CDCOccupational and environmental health,Aerosol transmission ChinaWPRWG47U YanagiMaleKogakuin UniversityMicrobial pollution in building environmentJapanWPRTCG48Hui-

307、Ling YenFemaleSchool of Public Health,The University of Hong KongEpidemiology,influenza,and virologyHong Kong SAR,ChinaWPRTCG49Kwok-Yung YuenMaleDepartment of Microbiology,The University of Hong KongInternal medicine,infectious diseasesHong Kong SAR,ChinaWPRTCG50Walter ZinggMaleZurich University Hos

308、pitalInfection prevention and controlSwitzerlandEURTCG*Regions were assigned by using WHO geographical regionsAFR:African Region AMR:Region of the AmericasCDC:Center for Disease Control and preventionEMR:Eastern Mediterranean RegionEUR:European RegionSAR China:Special Administrative Region of the Pe

309、oples Republic of ChinaSEAR:South-East Asian RegionTCG:Technical Consultation GroupWG:Working GroupWPR:Western Pacific Region.continuedAnnex 5.Summary of discussionsAreas of overall general agreementThe discussions of the global TCG,and engagement with others in the groups jurisdictions during the c

310、onsultation,have resulted in alignment on the following issues:IRPs exist on a continuum spectrum of sizes,and no definitive cut off points shouldbe applied to distinguish smaller from larger particles.Recognition of the continuumspectrum of sizes allows to move away from the dichotomy of previous a

311、nd com-monly known terms,such as aerosols(generally smaller particles)and droplets(generally larger particles);There was a consensus about how IRPs are expelled within a turbulent puff cloudthat moves through the air following emission from the human respiratory tract ofan infected person.The trajec

312、tory of IRPs is influenced by many factors includingthe force and volume of exhalation as well as including several environmental condi-tions,such as ambient air temperature,humidity,airflow magnitude and velocity anddistribution within a space.These factors coupled with the pathogens viability andi

313、nfectivity in the IRPs contribute to the transmission probability;There was agreement on the importance of adequate ventilation and airflow patternswithin indoor spaces to help mitigate the risk of transmission of IRPs;It was agreed that different pathogens can have different predominant,or mixes of

314、,modes of transmission.In addition,pathogens vary in their frequency,virulence,treatability,and potential impact on hosts and society.This means that transmis-sion prevention and mitigation measures need to be tailored differently for differentpathogens and settings.Hence,pathogen-and setting-specif

315、ic guidance regardingmitigation measures,including IPC guidance,is needed.There was recognition thatlumping mitigation measures for all transmission modes,for all pathogens,intoone basket,and trying to apply a“one size fits all”approach would be incorrect orimpractical;Despite a need to tailor mitig

316、ation measures to account for different transmissionscenarios as described above,most,but not all,agreed that using the more generaland broader term of transmission through the air to refer to the overall concept ofpathogens being transmitted through the air,and to cover the airborne transmis-sion/i

317、nhalation and direct deposition modes of transmission of IRPs outlined in thisdocument,was a useful descriptor,particularly when trying to explain these complexconcepts to the general public.Areas of non-consensus and concern regarding consequencesIt is recognized that several revisions of existing

318、terminology that have been put forth as a result of this global technical consultation(and summarized above)could have major ramifications for the use of those terms in other disciplines.If,as is recognized herewith,smaller IRPs are capable of being transmitted at both short-and long-range,then to e

319、ffectively counteract this risk,full(what is now known as)airborne 32Global technical consultation report on proposed terminology for pathogens that transmit through the air33precautions,which involves substantive IPC measures,such as use of respirators,with or with-out specialized hospital rooms et

320、c.,may need to be applied to all those at risk of the disease,if a precautionary principle is to be applied or applied selectively depending on the frequency,morbidity,and treatment options for different pathogens(which may vary widely between and within countries).This would have legal,logistic,operational and financial consequences that have global implications with regards to equity and access.AnnexesFor further information,contact:Science DivisionWorld Health Organization20 avenue Appia1211 Geneva 27SwitzerlandEmail:ttatconsultwho.intWebsite:https:/www.who.int/our-work/science-division