Impact of vaccination on new SARS-CoV-2 infections in the United Kingdom
Emma Pritchard, Philippa C Matthews, Nicole Stoesser, David W Eyre, Owen Gethings, Karina-Doris Vihta, Joel Jones, Thomas House, Harper VanSteenHouse, Iain Bell, John I Bell, John N Newton, Jeremy Farrar, Ian Diamond, Emma Rourke, Ruth Studley, Derrick Crook, Tim E A Peto, A Sarah Walker, Koen B Pouwels, Emma Pritchard, Philippa C Matthews, Nicole Stoesser, David W Eyre, Owen Gethings, Karina-Doris Vihta, Joel Jones, Thomas House, Harper VanSteenHouse, Iain Bell, John I Bell, John N Newton, Jeremy Farrar, Ian Diamond, Emma Rourke, Ruth Studley, Derrick Crook, Tim E A Peto, A Sarah Walker, Koen B Pouwels
Abstract
The effectiveness of COVID-19 vaccination in preventing new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections in the general community is still unclear. Here, we used the Office for National Statistics COVID-19 Infection Survey-a large community-based survey of individuals living in randomly selected private households across the United Kingdom-to assess the effectiveness of the BNT162b2 (Pfizer-BioNTech) and ChAdOx1 nCoV-19 (Oxford-AstraZeneca; ChAdOx1) vaccines against any new SARS-CoV-2 PCR-positive tests, split according to self-reported symptoms, cycle threshold value (<30 versus ≥30; as a surrogate for viral load) and gene positivity pattern (compatible with B.1.1.7 or not). Using 1,945,071 real-time PCR results from nose and throat swabs taken from 383,812 participants between 1 December 2020 and 8 May 2021, we found that vaccination with the ChAdOx1 or BNT162b2 vaccines already reduced SARS-CoV-2 infections ≥21 d after the first dose (61% (95% confidence interval (CI) = 54-68%) versus 66% (95% CI = 60-71%), respectively), with greater reductions observed after a second dose (79% (95% CI = 65-88%) versus 80% (95% CI = 73-85%), respectively). The largest reductions were observed for symptomatic infections and/or infections with a higher viral burden. Overall, COVID-19 vaccination reduced the number of new SARS-CoV-2 infections, with the largest benefit received after two vaccinations and against symptomatic and high viral burden infections, and with no evidence of a difference between the BNT162b2 and ChAdOx1 vaccines.
Conflict of interest statement
All authors have completed the International Committee of Medical Journal Editors uniform disclosure from at http://www.icmje.org/disclosure-of-interest/. D.W.E. declares lecture fees from Gilead outside of the submitted work. E.P., P.C.M., N.S., D.W.E., J.I.B., D.C., T.E.A.P., A.S.W. and K.B.P. are employees of the University of Oxford but were not involved in the development or production of the ChAdOx1 vaccine. J.I.B. acts as an unpaid advisor to Her Majesty’s Government on COVID-19 but does not sit on the vaccine task force and is not involved in procurement decisions. J.I.B. also sits on the board of Oxford Sciences Innovation, which has an investment in Vaccitech, which will receive a royalty from the ChAdOx1 vaccine if/when it makes a profit. H.V. reports personal fees from BioSpyder Technologies outside of the submitted work. Besides the funding mentioned above, A.S.W. also received grants from the Medical Research Council UK during the conduct of the study. There are no other relationships or activities that could appear to have influenced the submitted work.
© 2021. The Author(s).
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Source: PubMed