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.

Alexis Sentís ; Irina Kislaya ; Nathalie Nicolay ; Hinta Meijerink ; Jostein Starrfelt ; Iván Martínez-Baz ; Jesús Castilla ; Katrine Finderup Nielsen ; Christian Holm Hansen

; Hanne-Dorthe Emborg ; +6 more... Anthony Nardone ; Tarik Derrough ; Marta Valenciano ; Baltazar Nunes ; Susana Monge ; VEBIS-Lot4 working group ; (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.