An Observational Cohort Study on the Incidence of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infection and B.1.1.7 Variant Infection in Healthcare Workers by Antibody and Vaccination Status
Authors: Lumley Sheila F , Rodger Gillian , Constantinides Bede , Sanderson Nicholas , Chau Kevin K , Street Teresa L , O’Donnell Denise , Howarth Alison , Hatch Stephanie B , Marsden Brian D , Cox Stuart , James Tim , Warren Fiona , Peck Liam J , Ritter Thomas G , de Toledo Zoe , Warren Laura , Axten David , Cornall Richard J , Jones E Yvonne , Stuart David I , Screaton Gavin , Ebner Daniel , Hoosdally Sarah , Chand Meera , Crook Derrick W , O’Donnell Anne-Marie , Conlon Christopher P , Pouwels Koen B , Walker A Sarah , Peto Tim E A , Hopkins Susan , Walker Timothy M , Stoesser Nicole E , Matthews Philippa C , Jeffery Katie , Eyre David W ,   Oxford University Hospitals Staff Testing Group, Shibu Afrah , Curtis Aisling , Mighiu Alexandra , Manji Ali , Nezhentsev Andrey , Somanathan Arun , Khulusi Beinn , Holloway Ben , Rigler Caitlin , Virgo Charis , Fields Charlotte , Lee Charlotte , Daly Elizabeth , Hatton Elizabeth , Weeks Esme , McGivern Euan , Economides Greta , Fuchs Hannah , Jackson-Smith Harry , Tong Heather , Callard Helen , Clay Helen , Davies Henrietta , Jarratt Barnham Isaac , Sharma Ishta , Wilson Jack , Ward Jocelyn , Cutteridge Joseph , Kotowska Julia , Lee Kirsten , Ravi Krupa , Wilkins Laura , Cansdale Lottie , Bland Lucy , Farache Trajano Luiza , Chmura Magdalena , Lucey Maria , Pikoula Maria , Evans Meirian , Abbott Molly , Tamblyn Morwenna , Grant Oriane , Conway-Jones Rebecca , Toward Ross , Abhari Roxanna , Wolman Ruby , Hosseinzadeh Sara , Thomas Sarah , Madsen Tara , H Foord Thomas , Johnson Thomas , Perera Vimukthi , Shabir Zamin , Christott Thomas , Doherty George , W Fowler Philip , Karpe Fredrik , Kavanagh James , Martins Ferreira Lucas , J Neville Matt , Pickford Hayleah , Skelly Donal , Swann Jeremy , Cameron Sarah , Tamblin-Hopper Phoebe , Wolna Magda , Brown Rachael , Volk Denis , Yang-Turner Fan , Vaughan Alison , Bialek Adrian , Whitty Alison , Westlake Annie , Wozniak Barbara , Butler Bryony , Ferreira Claudio , Russell Danielle , Pether Dawn , Lawson Elaine , Ross Eleanor , Fragkouli Eleni , Sims Elizabeth , Mortimore Emma , Shaw Geraldine , Mullins Harriet , Caroll Harriett , Phillips Jane , Brown Jenny , Ponting Jess , Szczurkowska Justyna , Vilca Kim , Norris Kitty , Holland Louise , Luciw Michael , Gates Michelle , Layton Michelle , Antonucci Nicola , Bodo Noemi , Millard Rebecca , Lyden Sara , Young Sarah , Barot Simran , Cox Vanessa , Wharton Victoria , Thompson Zoe , Baby Anne , Bastable Jasmine , Cann Kathryn , Chohan Reena , Clarke Josie , Cogorno Gabriel , Cordy Samantha , Coward Georgina , Crawford-Jones David , Crawley Sean , Dobson Jack , Drummond Bronte , Dunn Laura , Edwin Caleb , Evans Simon , Fadzillah Mohamad , Gentry Jessica , Hill Sarah , Hobden Laura , Huda Nurul , Innes Gemma , Jarvis Scott , Jesuthasan Gerald , Jones Emma , Justice Anita , Kalimeris Elizabeth , Kirton Richard , Lashley Nakiah , Mason Sophie , Mobbs Alexander , Murugathasan Ahila , Mustoe Eleanor , Ngoke Gospel , Oakley Sarah , O’Sullivan Oliver , Odwin Kimberley , Oliver Jack , Pattrick Freyja , Pereira Claudia , Perry Simon , Potter Tom , Prentice Alexander , Ramage Sophie , Sanders Athena , Savage Kellyanne , Shimell Katherine , Terry Robin , Thornton Emma , Wareing Susan , Welbourne Annie , Wheatley Maddison , Butcher Lisa , D’Amato Gabriella , Moroney Ruth , Pill Gemma , Rylance-Knight Lydia , Sutton Claire , Salvagno Claudia , Tabirao Merline , Wright Sarah 
Published: July 2021

Abstract

Background
Natural and vaccine-induced immunity will play a key role in controlling the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. SARS-CoV-2 variants have the potential to evade natural and vaccine-induced immunity.

Methods
In a longitudinal cohort study of healthcare workers (HCWs) in Oxfordshire, United Kingdom, we investigated the protection from symptomatic and asymptomatic polymerase chain reaction (PCR)-confirmed SARS-CoV-2 infection conferred by vaccination (Pfizer-BioNTech BNT162b2, Oxford-AstraZeneca ChAdOx1 nCOV-19) and prior infection (determined using anti-spike antibody status), using Poisson regression adjusted for age, sex, temporal changes in incidence and role. We estimated protection conferred after 1 versus 2 vaccinations and from infections with the B.1.1.7 variant identified using whole genome sequencing.

Results
In total, 13 109 HCWs participated; 8285 received the Pfizer-BioNTech vaccine (1407 two doses), and 2738 the Oxford-AstraZeneca vaccine (49 two doses). Compared to unvaccinated seronegative HCWs, natural immunity and 2 vaccination doses provided similar protection against symptomatic infection: no HCW vaccinated twice had symptomatic infection, and incidence was 98% lower in seropositive HCWs (adjusted incidence rate ratio 0.02 [95% confidence interval {CI} &lt; .01–.18]). Two vaccine doses or seropositivity reduced the incidence of any PCR-positive result with or without symptoms by 90% (0.10 [95% CI .02–.38]) and 85% (0.15 [95% CI .08–.26]), respectively. Single-dose vaccination reduced the incidence of symptomatic infection by 67% (0.33 [95% CI .21–.52]) and any PCR-positive result by 64% (0.36 [95% CI .26–.50]). There was no evidence of differences in immunity induced by natural infection and vaccination for infections with S-gene target failure and B.1.1.7.

Conclusions
Natural infection resulting in detectable anti-spike antibodies and 2 vaccine doses both provide robust protection against SARS-CoV-2 infection, including against the B.1.1.7 variant.