Antibody responses are an important part of immunity after Coronavirus Disease 2019 (COVID-19) vaccination. However, antibody trajectories and the associated duration of protection after a second vaccine dose remain unclear. In this study, we investigated anti-spike IgG antibody responses and correlates of protection after second doses of ChAdOx1 or BNT162b2 vaccines for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the United Kingdom general population. In 222,493 individuals, we found significant boosting of anti-spike IgG by the second doses of both vaccines in all ages and using different dosing intervals, including the 3-week interval for BNT162b2. After second vaccination, BNT162b2 generated higher peak levels than ChAdOX1. Older individuals and males had lower peak levels with BNT162b2 but not ChAdOx1, whereas declines were similar across ages and sexes with ChAdOX1 or BNT162b2. Prior infection significantly increased antibody peak level and half-life with both vaccines. Anti-spike IgG levels were associated with protection from infection after vaccination and, to an even greater degree, after prior infection. At least 67% protection against infection was estimated to last for 2–3 months after two ChAdOx1 doses, for 5–8 months after two BNT162b2 doses in those without prior infection and for 1–2 years for those unvaccinated after natural infection. A third booster dose might be needed, prioritized to ChAdOx1 recipients and those more clinically vulnerable.
Bibliographical noteFunding Information: We are grateful for the support of all COVID-19 Infection Survey participants. This study is funded by the Department of Health and Social Care with in-kind support from the Welsh Government and the Department of Health on behalf of the Northern Ireland Government and the Scottish Government. J.W. is supported by the University of Oxford and the China Scholarship Council. A.S.W., T.E.A.P., N.S., D.E. and K.B.P. are supported by the National Institute for Health Research (NIHR) Health Protection Research Unit in Healthcare Associated Infections and Antimicrobial Resistance at the University of Oxford, in partnership with the UK Health Security Agency (UKHSA) (NIHR200915). A.S.W. and T.E.A.P. are also supported by the NIHR Oxford Biomedical Research Centre. K.B.P. is also supported by the Huo Family Foundation. A.S.W. is also supported by core support from the Medical Research Council UK to the MRC Clinical Trials Unit (MC_UU_12023/22) and is an NIHR Senior Investigator. P.C.M. is funded by Wellcome (intermediate fellowship, grant ref. 110110/Z/15/Z) and holds an NIHR Oxford BRC Senior Fellowship. D.W.E. is supported by a Robertson Fellowship and an NIHR Oxford BRC Senior Fellowship. N.S. is an Oxford Martin Fellow and holds an NIHR Oxford BRC Senior Fellowship. The views expressed are those of the authors and not necessarily those of the National Health Service, NIHR, Department of Health or UKHSA.
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Citation: Wei, J., Pouwels, K.B., Stoesser, N. et al. Antibody responses and correlates of protection in the general population after two doses of the ChAdOx1 or BNT162b2 vaccines. Nat Med (2022).