Waning of first- and second-dose ChAdOx1 and BNT162b2 COVID-19 vaccinations: a pooled target trial study of 12.9 million individuals in England, Northern Ireland, Scotland and Wales

Kerr, S. et al. (2023) Waning of first- and second-dose ChAdOx1 and BNT162b2 COVID-19 vaccinations: a pooled target trial study of 12.9 million individuals in England, Northern Ireland, Scotland and Wales. International Journal of Epidemiology, 52(1), pp. 22-31. (doi: 10.1093/ije/dyac199) (PMID:36272418) (PMCID:PMC9620314)

Abstract

Background: Several SARS-CoV-2 vaccines have been shown to provide protection against COVID-19 hospitalization and death. However, some evidence suggests that notable waning in effectiveness against these outcomes occurs within months of vaccination. We undertook a pooled analysis across the four nations of the UK to investigate waning in vaccine effectiveness (VE) and relative vaccine effectiveness (rVE) against severe COVID-19 outcomes. Methods: We carried out a target trial design for first/second doses of ChAdOx1(Oxford–AstraZeneca) and BNT162b2 (Pfizer–BioNTech) with a composite outcome of COVID-19 hospitalization or death over the period 8 December 2020 to 30 June 2021. Exposure groups were matched by age, local authority area and propensity for vaccination. We pooled event counts across the four UK nations. Results: For Doses 1 and 2 of ChAdOx1 and Dose 1 of BNT162b2, VE/rVE reached zero by approximately Days 60–80 and then went negative. By Day 70, VE/rVE was –25% (95% CI: –80 to 14) and 10% (95% CI: –32 to 39) for Doses 1 and 2 of ChAdOx1, respectively, and 42% (95% CI: 9 to 64) and 53% (95% CI: 26 to 70) for Doses 1 and 2 of BNT162b2, respectively. rVE for Dose 2 of BNT162b2 remained above zero throughout and reached 46% (95% CI: 13 to 67) after 98 days of follow-up. Conclusions: We found strong evidence of waning in VE/rVE for Doses 1 and 2 of ChAdOx1, as well as Dose 1 of BNT162b2. This evidence may be used to inform policies on timings of additional doses of vaccine.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Katikireddi, Professor Vittal
• Authors: Kerr, S., Bedston, S., Bradley, D. T., Joy, M., Lowthian, E., Mulholland, R. M., Akbari, A., Hobbs, F. D. R., Katikireddi, S. V., de Lusignan, S., Rudan, I., Torabi, F., Tsang, R. S. M., Lyons, R. A., Robertson, C., and Sheikh, A.
• College/School: College of Medical Veterinary and Life Sciences > School of Health & Wellbeing > MRC/CSO SPHSU
• Journal Name: International Journal of Epidemiology
• Publisher: Oxford University Press
• ISSN: 0300-5771
• ISSN (Online): 1464-3685
• Published Online: 22 October 2022
• Copyright Holders: Copyright © 2022 The Author(s)
• First Published: First published in International Journal of Epidemiology 52(1): 22-31
• Publisher Policy: Reproduced under a Creative Commons License