Estimation of COVID-19 vaccine effectiveness against hospitalisation in individuals aged ≥ 65 years using electronic health registries; a pilot study in four EU/EEA countries, October 2021 to March 2022.

Sentís, A; Kislaya, I; Nicolay, N; Meijerink, H; Starrfelt, J; Martínez-Baz, I; Castilla, J; Nielsen, KF; Hansen, CH

; Emborg, H; +6 more...Nardone, A; Derrough, T; Valenciano, M; Nunes, B; Monge, S; VEBIS-Lot4 working group and (2022) Estimation of COVID-19 vaccine effectiveness against hospitalisation in individuals aged ≥ 65 years using electronic health registries; a pilot study in four EU/EEA countries, October 2021 to March 2022. Eurosurveillance, 27 (30). ISSN 1560-7917 DOI: 10.2807/1560-7917.ES.2022.27.30.2200551

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By employing a common protocol and data from electronic health registries in Denmark, Navarre (Spain), Norway and Portugal, we estimated vaccine effectiveness (VE) against hospitalisation due to COVID-19 in individuals aged ≥ 65 years old, without previous documented infection, between October 2021 and March 2022. VE was higher in 65-79-year-olds compared with ≥ 80-year-olds and in those who received a booster compared with those who were primary vaccinated. VE remained high (ca 80%) between ≥ 12 and < 24 weeks after the first booster administration, and after Omicron became dominant.