RESUMEN
Influenza A viruses circulated in Europe from September 2023 to January 2024, with influenza A(H1N1)pdm09 predominance. We provide interim 2023/24 influenza vaccine effectiveness (IVE) estimates from two European studies, covering 10 countries across primary care (EU-PC) and hospital (EU-H) settings. Interim IVE was higher against A(H1N1)pdm09 than A(H3N2): EU-PC influenza A(H1N1)pdm09 IVE was 53% (95%â¯CI:â¯41â¯toâ¯63) and 30% (95%â¯CI:â¯-3â¯toâ¯54) against influenza A(H3N2). For EU-H, these were 44% (95%â¯CI:â¯30â¯toâ¯55) and 14% (95%â¯CI:â¯-32â¯toâ¯43), respectively.
Asunto(s)
Subtipo H1N1 del Virus de la Influenza A , Vacunas contra la Influenza , Gripe Humana , Humanos , Gripe Humana/epidemiología , Gripe Humana/prevención & control , Virus de la Influenza B , Subtipo H3N2 del Virus de la Influenza A , Vacunación , Estudios de Casos y Controles , Estaciones del Año , Hospitales , Atención Primaria de SaludRESUMEN
In autumn 2023, European vaccination campaigns predominantly administered XBB.1.5 vaccine. In a European multicentre study, we estimated 2023 COVID-19 vaccine effectiveness (VE) against laboratory-confirmed symptomatic infection at primary care level between September 2023 and January 2024. Using a test-negative case-control design, we estimated VE in the target group for COVID-19 vaccination overall and by time since vaccination. We included 1057 cases and 4397 controls. Vaccine effectiveness was 40 % (95 % CI: 26-53 %) overall, 48 % (95 % CI: 31-61 %) among those vaccinated < 6 weeks of onset and 29 % (95 % CI: 3-49 %) at 6-14 weeks. Our results suggest that COVID-19 vaccines administered to target groups during the autumn 2023 campaigns showed clinically significant effectiveness against laboratory-confirmed, medically attended symptomatic SARS-CoV-2 infection in the 3 months following vaccination. A longer study period will allow for further variant-specific COVID-19 VE estimates, better understanding decline in VE and informing booster administration policies.