{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,7,3]],"date-time":"2025-07-03T04:22:36Z","timestamp":1751516556215,"version":"3.41.0"},"reference-count":12,"publisher":"Scientific Scholar","issue":"5&6","content-domain":{"domain":["lww.com","ovid.com"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[2022,5]]},"abstract":"\n Background & objectives:<\/jats:title>\n Vaccination against COVID-19 induces spike protein-binding IgG antibodies, a robust correlate of protection against COVID-19. This study was undertaken to assess the humoral response after completion of both the doses of ChAdOx1 nCoV vaccine in healthcare workers (HCWs) at a tertiary care health centre in India.<\/jats:p>\n <\/jats:sec>\n \n Methods:<\/jats:title>\n A cross-sectional COVID-19 vaccine-induced antibody study was conducted among HCWs. IgG antibodies against spike protein were measured at least 28 days after the first dose and the second dose of vaccination in both SARS CoV-2 na\u00efve and recovered HCWs. Mean and median antibody titre following each dose of vaccine and its association with age, gender, co-morbidities and factors such as exercise, stress and sleep deprivation were also explored.<\/jats:p>\n <\/jats:sec>\n \n Results:<\/jats:title>\n Among the 200 vaccine recipients, 91.5 per cent showed seroconversion after the first dose and 99.5 per cent after the second dose. The mean titre after the second dose was significantly higher when compared to the first dose (12.68\u00b14.17 vs<\/jats:italic>. 9.83\u00b16.3, P<\/jats:italic>=0.001). More than half (54%) had high antibody titre \u226512 S\/Co (Signal\/cut-off). Previous COVID-19 infection was the single most important factor influencing antibody production, where the mean titre just after a single dose [mean-17.81\u00b15.94, median-20.5 (interquartile range [IQR]-3.7)] surpassed the titre after the second dose in SARS CoV-2 na\u00efve individuals [mean-12.29\u00b14.00, median-12.8 (IQR-3.7), P<\/jats:italic>=0.001]. Furthermore, 28 per cent of vaccinees showed a reduction in titre after the second dose. The mean fall in titre was 2.25\u00b11.40 and was more pronounced in males, the younger age group and those with previous COVID-19 infection.<\/jats:p>\n <\/jats:sec>\n \n Interpretation & conclusions:<\/jats:title>\n ChAdOx1 nCov-19 vaccine after two doses elicited an excellent immune response. However, greater immunogenicity after the first dose was seen among those with previous COVID-19 infection, even surpassing the titre achieved by the second dose of vaccine in SARS CoV-2 na\u00efve recipients. A fall in antibody titre after the second dose is a matter of concern and requires further studies.<\/jats:p>\n <\/jats:sec>","DOI":"10.4103\/ijmr.ijmr_1917_21","type":"journal-article","created":{"date-parts":[[2022,10,3]],"date-time":"2022-10-03T09:59:52Z","timestamp":1664791192000},"page":"499-504","update-policy":"https:\/\/doi.org\/10.1097\/lww.0000000000001000","source":"Crossref","is-referenced-by-count":2,"title":["A study on seroconversion following first & second doses of ChAdOx1 nCoV-19 vaccine in central Kerala"],"prefix":"10.25259","volume":"155","author":[{"given":"Sangeetha Merrin","family":"Varghese","sequence":"first","affiliation":[{"name":"Department of Community Medicine, Thiruvalla, Kerala, India"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"George Chandy","family":"Mateethra","sequence":"additional","affiliation":[{"name":"Department of Gastroenterology, Thiruvalla, Kerala, India"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Geomcy","family":"George","sequence":"additional","affiliation":[{"name":"Department of Oncology, Thiruvalla, Kerala, India"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Vishnu S.","family":"Chandran","sequence":"additional","affiliation":[{"name":"Department of Rheumatology, Thiruvalla, Kerala, India"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Grace Mary","family":"John","sequence":"additional","affiliation":[{"name":"Believers Church Medical College, Thiruvalla, Kerala, India"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Levin Thamban","family":"Varghese","sequence":"additional","affiliation":[{"name":"Believers Church Medical College, Thiruvalla, Kerala, India"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Nithin K.","family":"Mammen","sequence":"additional","affiliation":[{"name":"Believers Church Medical College, Thiruvalla, Kerala, India"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"V.","family":"Vinayak","sequence":"additional","affiliation":[{"name":"Believers Church Medical College, Thiruvalla, Kerala, India"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"10894","published-online":{"date-parts":[[2022,10,28]]},"reference":[{"key":"B2-20241212","doi-asserted-by":"crossref","first-page":"4423","DOI":"10.1016\/j.vaccine.2021.05.063","article-title":"Evidence for antibody as a protective correlate for COVID-19 vaccines","volume":"39","author":"Earle","year":"2021","journal-title":"Vaccine"},{"key":"B3-20241212","first-page":"2071","article-title":"Implications of vaccination and waning immunity","volume":"276","author":"Heffernan","year":"2009","journal-title":"Proc Biol Sci"},{"key":"B4-20241212","doi-asserted-by":"crossref","first-page":"491","DOI":"10.1038\/d41586-021-01359-3","article-title":"Mix-and-match COVID vaccines trigger potent immune 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Brazil, South Africa, and the UK","volume":"397","author":"Voysey","year":"2021","journal-title":"Lancet"},{"key":"B14-20241212","doi-asserted-by":"crossref","first-page":"1205","DOI":"10.1038\/s41591-021-01377-8","article-title":"Neutralizing antibody levels are highly predictive of immune protection from symptomatic SARS-CoV-2 infection","volume":"27","author":"Khoury","year":"2021","journal-title":"Nat Med"},{"key":"B15-20241212","doi-asserted-by":"crossref","first-page":"479","DOI":"10.1016\/S0140-6736(20)31605-6","article-title":"Immunogenicity and safety of a recombinant adenovirus type-5-vectored COVID-19 vaccine in healthy adults aged 18 years or older:A randomised, double-blind, placebo-controlled, phase 2 trial","volume":"396","author":"Zhu","year":"2020","journal-title":"Lancet"},{"key":"B16-20241212","doi-asserted-by":"crossref","first-page":"1140","DOI":"10.1038\/s41564-021-00947-3","article-title":"Antibody responses to SARS-CoV-2 vaccines in 45,965 adults from the 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