{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,13]],"date-time":"2026-07-13T23:51:13Z","timestamp":1783986673442,"version":"3.55.0"},"reference-count":28,"publisher":"Wiley","issue":"10","license":[{"start":{"date-parts":[[2023,10,3]],"date-time":"2023-10-03T00:00:00Z","timestamp":1696291200000},"content-version":"vor","delay-in-days":2,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100004423","name":"World Health Organization","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100004423","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Influenza Resp Viruses"],"published-print":{"date-parts":[[2023,10]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:sec><jats:title>Background<\/jats:title><jats:p>Healthcare workers (HCWs) have suffered considerable morbidity and mortality during the COVID\u201019 pandemic. Few studies have evaluated the CoronaVac vaccine effectiveness (VE), particularly in Eastern Europe, where the vaccine has been widely used.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>We conducted a prospective cohort study among HCWs in seven hospitals in Baku, Azerbaijan between May 17 and November 30, 2021, to evaluate primary series (two\u2010dose) CoronaVac VE against symptomatic SARS\u2010CoV\u20102 infection. Participants completed weekly symptom questionnaires, provided nasopharyngeal swabs for SARS\u2010CoV\u20102 RT\u2010PCR testing when symptomatic, and provided serology samples at enrollment that were tested for anti\u2010spike and anti\u2010nucleocapsid antibodies. We estimated VE as (1 \u2013 hazard ratio)*100 using a Cox proportional hazards model with vaccination status as a time\u2010varying exposure, adjusting for hospital and previous SARS\u2010CoV\u20102 infection status.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>We enrolled 1582 HCWs. At enrollment, 1040 (66%) had received two doses of CoronaVac; 421 (27%) were unvaccinated. During the study period, 72 PCR\u2010positive SARS\u2010CoV\u20102 infections occurred; 36\/39 (92%) sequenced samples were classified as Delta variants. Primary series VE against COVID\u201019 illness was 29% (95% CI: \u221251%; 67%) for the entire analysis period. For the Delta\u2010only period (July 1\u2013November 30, 2021), primary series VE was 19% (95% CI: \u221281%; 64%). For the entire analysis period, primary series VE was 39% (95% CI: \u221240%; 73%) for HCWs vaccinated within 14\u2013149\u2009days and 19% (95% CI: \u221281%; 63%) for those vaccinated \u2265150\u2009days.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>During a period in Azerbaijan characterized by mostly Delta circulation, VE point estimates suggested that primary series CoronaVac protected nearly 1 in 3 HCWs against COVID\u201019, but 95% confidence intervals were wide, with lower bounds that crossed zero, reflecting the limited precision of our VE estimates. Our findings underscore the need to consider booster doses for individuals who have received the primary series of CoronaVac.<\/jats:p><\/jats:sec>","DOI":"10.1111\/irv.13147","type":"journal-article","created":{"date-parts":[[2023,10,4]],"date-time":"2023-10-04T09:11:04Z","timestamp":1696410664000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["The effectiveness of primary series CoronaVac vaccine in preventing COVID\u201019 illness: A prospective cohort study among healthcare workers in Azerbaijan, May\u2013November 2021"],"prefix":"10.1111","volume":"17","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-5532-7276","authenticated-orcid":false,"given":"Mark A.","family":"Katz","sequence":"first","affiliation":[{"name":"World Health Organization Regional Office for Europe  Copenhagen Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Madelyn Yiseth","family":"Rojas Castro","sequence":"additional","affiliation":[{"name":"Epiconcept  Paris France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nabil","family":"Seyidov","sequence":"additional","affiliation":[{"name":"Public Health and Reforms Center Ministry of Health  Baku Azerbaijan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"M. Trent","family":"Herdman","sequence":"additional","affiliation":[{"name":"UK Field Epidemiology Training Programme UK Health Security Agency  London UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Samir","family":"Mehdiyev","sequence":"additional","affiliation":[{"name":"Public Health and Reforms Center Ministry of Health  Baku Azerbaijan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"C. Jason","family":"McKnight","sequence":"additional","affiliation":[{"name":"World Health Organization Regional Office for Europe  Copenhagen Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6284-3412","authenticated-orcid":false,"given":"Alina","family":"Guseinova","sequence":"additional","affiliation":[{"name":"World Health Organization Regional Office for Europe  Copenhagen Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Radu","family":"Cojocaru","sequence":"additional","affiliation":[{"name":"World Health Organization Regional Office for Europe  Copenhagen Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jason","family":"Doran","sequence":"additional","affiliation":[{"name":"UK Field Epidemiology Training Programme UK Health Security Agency  London UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Barbara","family":"M\u00fchlemann","sequence":"additional","affiliation":[{"name":"Institute of Virology, Charit\u00e9\u2013Universit\u00e4tsmedizin Berlin, corporate member of Freie Universit\u00e4t Berlin Humboldt\u2010 Universit\u00e4t zu Berlin, and Berlin Institute of Health  Berlin Germany"},{"name":"German Centre for Infection Research (DZIF), partner site Charit\u00e9  Berlin Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Christian","family":"Drosten","sequence":"additional","affiliation":[{"name":"Institute of Virology, Charit\u00e9\u2013Universit\u00e4tsmedizin Berlin, corporate member of Freie Universit\u00e4t Berlin Humboldt\u2010 Universit\u00e4t zu Berlin, and Berlin Institute of Health  Berlin Germany"},{"name":"German Centre for Infection Research (DZIF), partner site Charit\u00e9  Berlin 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