Comparison of two methods for the estimation of COVID-19 vaccine effectiveness of the autumnal booster within the VEBIS-EHR network in 2022/23
Monge, Susana Humphreys, James Nicolay, Nathalie Braeye, Toon Van Evercooren, Izaak Hansen, Christian Holm Emborg, Hanne-Dorthe Fabiani, Massimo Sacco, Chiara Castilla, Jesús
Monge, Susana
Humphreys, James
Nicolay, Nathalie
Braeye, Toon
Van Evercooren, Izaak
Hansen, Christian Holm
Emborg, Hanne-Dorthe
Fabiani, Massimo
Sacco, Chiara
Castilla, Jesús
Series / Report no.
Open Access
Type
Article
Language
en
Date of publication
2025-03-17
Year of publication
Research Projects
Organizational Units
Journal Issue
Title
Comparison of two methods for the estimation of COVID-19 vaccine effectiveness of the autumnal booster within the VEBIS-EHR network in 2022/23
Translated Title
Published in
Epidemiol Infect 2025; 153:e54
Abstract
Within an infrastructure to monitor vaccine effectiveness (VE) against hospitalization due to COVID-19 and COVID-19 related deaths from November 2022 to July 2023 in seven countries in real-world conditions (VEBIS network), we compared two approaches: (a) estimating VE of the first, second or third COVID-19 booster doses administered during the autumn of 2022, and (b) estimating VE of the autumn vaccination dose regardless of the number of prior doses (autumnal booster approach). Retrospective cohorts were constructed using Electronic Health Records at each participating site. Cox regressions with time-changing vaccination status were fit and site-specific estimates were combined using random-effects meta-analysis. VE estimates with both approaches were mostly similar, particularly shortly after the start of the vaccination campaign, and showed a similar timing of VE waning. However, autumnal booster estimates were more precise and showed a clearer trend, particularly compared to third booster estimates, as calendar time increased after the vaccination campaign and during periods of lower SARS-CoV-2 activity. Moreover, the decrease in protection by increasing calendar time was more clear and precise than when comparing protection by number of doses. Therefore, estimating VE under an autumnal booster framework emerges as a preferred method for future monitoring of COVID-19 vaccination campaigns.