{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"institution":[{"name":"medRxiv"}],"indexed":{"date-parts":[[2026,1,16]],"date-time":"2026-01-16T13:02:51Z","timestamp":1768568571267,"version":"3.49.0"},"posted":{"date-parts":[[2025,5,1]]},"group-title":"Infectious Diseases (except HIV\/AIDS)","reference-count":41,"publisher":"openRxiv","license":[{"start":{"date-parts":[[2025,5,1]],"date-time":"2025-05-01T00:00:00Z","timestamp":1746057600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"accepted":{"date-parts":[[2025,12,2]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                <jats:p>\n                  A previous controlled human influenza transmission trial produced minimal transmission using nasal inoculation of an egg adapted virus. Therefore, we implemented a new trial with naturally infected Donors. We recruited healthy Recipients for four, two-week hotel quarantine cohorts and naturally infected, qRT-PCR confirmed Donors for two cohorts. Five Donors (mean age: 21; 80% female; two H1N1, three H3N2, one for cohort 24b and 4 for 24c, Jan-Feb 2024) exposed Recipients (mean age: 36; 55% female, eight in cohort 24b and 3 in 24c) in a hotel room with limited ventilation but a high air recirculation rate. We collected exhaled breath, ambient and personal bioaerosols, fomite swabs, and sera, and analyzed samples using dPCR and fluorescent focus assays, hemagglutination inhibition (HAI) assay, and enzyme-linked immunosorbent assay (ELISA). Compared with previously studied community-acquired influenza cases, we detected viral RNA (44%) and culturable virus (6%) less frequently and measured fewer viral RNA copies (79 \u2013 8.9\u00d710\n                  <jats:sup>3<\/jats:sup>\n                  copies\/30-min) in Donors\u2019 exhaled fine aerosols. One of 23 surface swab samples was culture positive. At admission, 8 of 11 Recipients had HAI titers \u226410 but 9 of 11 had stronger binding antibody responses than Donors against vaccine strains corresponding to Donor viruses. No Recipient developed influenza-like illness, PCR-positive respiratory samples, or serological evidence of infection. Potential explanations and insights regarding lack of transmission include importance of cough and seasonal variation in viral aerosol shedding by Donors, of potential cross-reactive immunity in middle-aged Recipients with decades of exposure, and of exposure to concentrated exhaled breath plumes limited by rapid air mixing from environmental controls that distributed aerosols evenly. Future trials over multiple seasons, Donors that cough, younger recipients, and environments that preserve normal exhaled breath plumes will be required to observe transmission from naturally infected Donors under controlled conditions and generate new insights into influenza transmission dynamics.\n                <\/jats:p>\n                <jats:sec>\n                  <jats:title>Author Summary<\/jats:title>\n                  <jats:p>Human-to-human influenza virus transmission under controlled conditions could provide insights leading to better control of epidemics and pandemics. However, a previous study using laboratory adapted viruses produced minimal transmission. Therefore, we aimed to study transmission from people naturally infected with circulating viruses. We recruited four cohorts of healthy volunteer Recipients to stay in a quarantine hotel for two weeks. We could not recruit Donors for the first two cohorts. In the last two cohorts, one Donor exposed eight Recipients in the first and four Donors exposed three Recipients in the second. The Donors coughed infrequently and shed less virus into the air than we had observed during previous influenza seasons. No Recipients became infected. Possible explanations include that people infected during mild influenza seasons or who cough very little may be minimally contagious. Our middle-aged Recipient cohorts were older than Donors and possibly less susceptible to infection because of additional years of vaccination and infection. Finally, environmental controls in the hotel distributed aerosols evenly but reduced short-range exposure to concentrated clouds of exhaled breath that may play an important role in transmission. New designs will need to address these issues.<\/jats:p>\n                <\/jats:sec>","DOI":"10.1101\/2025.04.28.25326458","type":"posted-content","created":{"date-parts":[[2025,5,1]],"date-time":"2025-05-01T11:35:11Z","timestamp":1746099311000},"source":"Crossref","is-referenced-by-count":0,"title":["Evaluating Modes of Influenza Transmission (EMIT-2): Insights from a Controlled Human Influenza Virus Infection Transmission Trial (CHIVITT)"],"prefix":"10.64898","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5705-0138","authenticated-orcid":false,"given":"Jianyu","family":"Lai","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hamed","family":"Sobhani","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kristen K.","family":"Coleman","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"S.-H. Sheldon","family":"Tai","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Filbert","family":"Hong","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Isabel Sierra","family":"Maldonado","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yi","family":"Esparza","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kathleen M.","family":"McPhaul","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Shengwei","family":"Zhu","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Don L.","family":"DeVoe","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3138-5965","authenticated-orcid":false,"given":"Justin R.","family":"Ortiz","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Shuo","family":"Chen","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Temima","family":"Yellin","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Juan Manuel","family":"Carreno","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Florian","family":"Krammer","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6297-7154","authenticated-orcid":false,"given":"Benjamin J.","family":"Cowling","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9352-7877","authenticated-orcid":false,"given":"Aubree","family":"Gordon","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7741-5536","authenticated-orcid":false,"given":"Wilbur H.","family":"Chen","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jelena","family":"Srebric","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0550-7834","authenticated-orcid":false,"given":"Donald K.","family":"Milton","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"name":"the EMIT-2 Study Team","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"54368","reference":[{"key":"2025120401201065000_2025.04.28.25326458v4.1","doi-asserted-by":"publisher","DOI":"10.1111\/irv.12486"},{"key":"2025120401201065000_2025.04.28.25326458v4.2","doi-asserted-by":"publisher","DOI":"10.1097\/EDE.0b013e3182a67448"},{"key":"2025120401201065000_2025.04.28.25326458v4.3","doi-asserted-by":"publisher","DOI":"10.1093\/aje\/kwv054"},{"key":"2025120401201065000_2025.04.28.25326458v4.4","doi-asserted-by":"publisher","DOI":"10.1086\/656740"},{"key":"2025120401201065000_2025.04.28.25326458v4.5","doi-asserted-by":"publisher","DOI":"10.1038\/nrmicro1208"},{"key":"2025120401201065000_2025.04.28.25326458v4.6","doi-asserted-by":"publisher","DOI":"10.1186\/1471-2334-14-480"},{"key":"2025120401201065000_2025.04.28.25326458v4.7","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.1716561115"},{"key":"2025120401201065000_2025.04.28.25326458v4.8","doi-asserted-by":"crossref","first-page":"1935","DOI":"10.1038\/ncomms2922","article-title":"Aerosol transmission is an important mode of influenza A virus spread","volume":"4","year":"2013","journal-title":"Nature Communications"},{"key":"2025120401201065000_2025.04.28.25326458v4.9","unstructured":"World Health Organization. Global technical consultation report on proposed terminology for pathogens that transmit through the air. 2024. Available at: https:\/\/www.who.int\/publications\/m\/item\/global-technical-consultation-report-on-proposed-terminology-for-pathogens-that-transmit-through-the-air."},{"key":"2025120401201065000_2025.04.28.25326458v4.10","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1111\/ina.12786","article-title":"Basic routes of transmission of respiratory pathogens-A new proposal for transmission categorization based on respiratory spray, inhalation, and touch","volume":"31","year":"2021","journal-title":"Indoor Air"},{"key":"2025120401201065000_2025.04.28.25326458v4.11","doi-asserted-by":"crossref","unstructured":"Tellier R , Li Y , Cowling BJ , Tang JW . Recognition of aerosol transmission of infectious agents: a commentary. BMC Infectious Diseases 2019; 19:101.","DOI":"10.1186\/s12879-019-3707-y"},{"key":"2025120401201065000_2025.04.28.25326458v4.12","doi-asserted-by":"publisher","DOI":"10.1093\/infdis\/jiy103"},{"key":"2025120401201065000_2025.04.28.25326458v4.13","unstructured":"RFA-AI-25-035: Influenza Transmission Research Consortium (P01 Clinical Trial Optional). Available at: https:\/\/grants.nih.gov\/grants\/guide\/rfa-files\/RFA-AI-25-035.html. Accessed 2 September 2025."},{"key":"2025120401201065000_2025.04.28.25326458v4.14","doi-asserted-by":"publisher","DOI":"10.1111\/irv.12790"},{"key":"2025120401201065000_2025.04.28.25326458v4.15","doi-asserted-by":"crossref","first-page":"e1008704","DOI":"10.1371\/journal.ppat.1008704","article-title":"Minimal transmission in an influenza A (H3N2) human challenge-transmission model within a controlled exposure environment","volume":"16","year":"2020","journal-title":"PLoS Pathog"},{"key":"2025120401201065000_2025.04.28.25326458v4.16","doi-asserted-by":"crossref","first-page":"e70129","DOI":"10.1111\/irv.70129","article-title":"Comparison of Viral Aerosol Shedding by Mild and Moderately Symptomatic Community-Acquired and Nasally Inoculated Influenza A(H3) Infection","volume":"19","year":"2025","journal-title":"Influenza Other Respir Viruses"},{"key":"2025120401201065000_2025.04.28.25326458v4.17","doi-asserted-by":"publisher","DOI":"10.1093\/oxfordjournals.aje.a112560"},{"key":"2025120401201065000_2025.04.28.25326458v4.18","unstructured":"Sobhani H , Vanama G , Coleman K , et al. Numerical Exposure Assessment in a Densely Populated, Well-mixed Room with Low Ventilation (In Preparation). 2025;"},{"key":"2025120401201065000_2025.04.28.25326458v4.19","doi-asserted-by":"crossref","first-page":"2033","DOI":"10.3390\/v15102033","article-title":"Influenza A and B Viruses in Fine Aerosols of Exhaled Breath Samples from Patients in Tropical Singapore","volume":"15","year":"2023","journal-title":"Viruses"},{"key":"2025120401201065000_2025.04.28.25326458v4.20","doi-asserted-by":"crossref","first-page":"1189","DOI":"10.1111\/ina.12701","article-title":"Quantitative aerobiologic analysis of an influenza human challenge-transmission trial","volume":"30","year":"2020","journal-title":"Indoor Air"},{"key":"2025120401201065000_2025.04.28.25326458v4.21","unstructured":"Wells WF . Airborne Contagion and Air Hygiene: An Ecological Study of Droplet Infection. Cambridge, MA: Harvard University Press, 1955."},{"key":"2025120401201065000_2025.04.28.25326458v4.22","doi-asserted-by":"crossref","first-page":"786","DOI":"10.1093\/cid\/ciac846","article-title":"Exhaled Breath Aerosol Shedding of Highly Transmissible Versus Prior Severe Acute Respiratory Syndrome Coronavirus 2 Variants","volume":"76","year":"2023","journal-title":"Clin Infect Dis"},{"key":"2025120401201065000_2025.04.28.25326458v4.23","unstructured":"Zhou J , Singanayagam A , Goonawardane N , et al. Viral emissions into the air and environment after SARS-CoV-2 human challenge: a phase 1, open label, first-in-human study. The Lancet Microbe 2023; 0. Available at: https:\/\/www.thelancet.com\/journals\/lanmic\/article\/PIIS2666-5247(23)00101-5\/fulltext#. Accessed 11 June 2023."},{"key":"2025120401201065000_2025.04.28.25326458v4.24","unstructured":"Vargas-Maldonado N , Shetty N , Ferreri LM , et al. Controlled human influenza infection reveals heterogeneous expulsion of infectious virus into air. 2025; :2025.11.03.25339190. Available at: https:\/\/www.medrxiv.org\/content\/10.1101\/2025.11.03.25339190v1. Accessed 17 November 2025."},{"key":"2025120401201065000_2025.04.28.25326458v4.25","doi-asserted-by":"crossref","first-page":"434","DOI":"10.3390\/vaccines8030434","article-title":"Influenza A Virus Vaccination: Immunity, Protection, and Recent Advances Toward A Universal Vaccine","volume":"8","year":"2020","journal-title":"Vaccines (Basel)"},{"key":"2025120401201065000_2025.04.28.25326458v4.26","doi-asserted-by":"publisher","DOI":"10.1016\/j.epidem.2019.100373"},{"key":"2025120401201065000_2025.04.28.25326458v4.27","first-page":"351","article-title":"Indirect health effects of relative humidity in indoor environments","volume":"65","year":"1986","journal-title":"Environ Health Perspect"},{"key":"2025120401201065000_2025.04.28.25326458v4.28","unstructured":"ASHRAE. Technical FAQ ID 92: What are the recommended temperature and humidity levels for indoor environments? 2014; Available at: https:\/\/www.ashrae.org\/File%20Library\/Technical%20Resources\/Technical%20FAQs\/TC-02.01-FAQ-92.pdf."},{"key":"2025120401201065000_2025.04.28.25326458v4.29","unstructured":"ASHE: Mgt Mono - Literature Review: Room Ventilation and Airborne Disease Transmission | ASHE. Available at: https:\/\/www.ashe.org\/management_monographs\/mg2013memarzadeh. Accessed 19 November 2025."},{"key":"2025120401201065000_2025.04.28.25326458v4.30","doi-asserted-by":"publisher","DOI":"10.7326\/0003-4819-133-10-200011210-00010"},{"key":"2025120401201065000_2025.04.28.25326458v4.31","doi-asserted-by":"crossref","unstructured":"Li W , Chong A , Hasama T , et al. Effects of ceiling fans on airborne transmission in an air-conditioned space. Building and Environment 2021; 198:107887.","DOI":"10.1016\/j.buildenv.2021.107887"},{"key":"2025120401201065000_2025.04.28.25326458v4.32","doi-asserted-by":"crossref","first-page":"100039","DOI":"10.1016\/j.indenv.2024.100039","article-title":"Should we use ceiling fans indoors to reduce the risk of transmission of infectious aerosols?","volume":"1","year":"2024","journal-title":"Indoor Environments"},{"key":"2025120401201065000_2025.04.28.25326458v4.33","doi-asserted-by":"publisher","DOI":"10.1034\/j.1600-0668.2002.08126.x"},{"key":"2025120401201065000_2025.04.28.25326458v4.34","doi-asserted-by":"publisher","DOI":"10.1093\/infdis\/156.3.442"},{"key":"2025120401201065000_2025.04.28.25326458v4.35","doi-asserted-by":"publisher","DOI":"10.1016\/j.jbi.2008.08.010"},{"key":"2025120401201065000_2025.04.28.25326458v4.36","doi-asserted-by":"publisher","DOI":"10.1080\/02786826.2012.762973"},{"key":"2025120401201065000_2025.04.28.25326458v4.37","doi-asserted-by":"publisher","DOI":"10.1039\/b609083d"},{"key":"2025120401201065000_2025.04.28.25326458v4.38","doi-asserted-by":"crossref","first-page":"145","DOI":"10.3390\/ijerph14020145","article-title":"Review and Extension of CO2-Based Methods to Determine Ventilation Rates with Application to School Classrooms","volume":"14","year":"2017","journal-title":"Int J Environ Res Public Health"},{"key":"2025120401201065000_2025.04.28.25326458v4.39","doi-asserted-by":"crossref","unstructured":"Sobhani H , Zhu S , Srebric J . Hotels as Quarantine Facilities with Airborne Virus Controls. Building and Environment 2025; :112765.","DOI":"10.1016\/j.buildenv.2025.112765"},{"key":"2025120401201065000_2025.04.28.25326458v4.40","doi-asserted-by":"crossref","first-page":"1821","DOI":"10.3201\/eid2707.210462","article-title":"Multiplex Real-Time Reverse Transcription PCR for Influenza A Virus, Influenza B Virus, and Severe Acute Respiratory Syndrome Coronavirus 2","volume":"27","year":"2021","journal-title":"Emerg Infect Dis"},{"key":"2025120401201065000_2025.04.28.25326458v4.41","doi-asserted-by":"crossref","unstructured":"Takada K , Kawakami C , Fan S , et al. A humanized MDCK cell line for the efficient isolation and propagation of human influenza viruses. Nat Microbiol 2019;","DOI":"10.1038\/s41564-019-0433-6"}],"container-title":[],"original-title":[],"link":[{"URL":"https:\/\/syndication.highwire.org\/content\/doi\/10.1101\/2025.04.28.25326458","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,1,15]],"date-time":"2026-01-15T20:34:48Z","timestamp":1768509288000},"score":1,"resource":{"primary":{"URL":"http:\/\/medrxiv.org\/lookup\/doi\/10.1101\/2025.04.28.25326458"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,5,1]]},"references-count":41,"URL":"https:\/\/doi.org\/10.1101\/2025.04.28.25326458","relation":{},"subject":[],"published":{"date-parts":[[2025,5,1]]},"subtype":"preprint"}}