BACKGROUND
We estimated the XBB.1.5 vaccine effectiveness (VE) against COVID-19 hospitalization and death in Belgium, Denmark, Italy, Portugal, Spain (Navarre), and Sweden following the 2023-24 fall vaccination campaign among immunocompromised persons (ICPs).
RESEARCH DESIGN AND METHODS
We conducted a multi-country retrospective cohort study using electronic health records. Study sites identified ICPs aged ≥18 years through a common set of immunocompromising conditions and follow-up started the first day of the 2023 vaccination campaign until 12 months later. VE was calculated by time since vaccination (14-59, 60-119, 120-179, 180-365 days after vaccination) for ICPs by pooling study site level confounder adjusted hazard ratios (aHR) of vaccination, estimated with Cox proportional hazards regression models, using a random effect meta-analysis with VE = 100 × (1-pooled aHR).
RESULTS
The XBB.1.5 VE was 52% (95% confidence interval (CI): 41 to 60) and 75% (95%CI: 60 to 84) against hospitalization and death, respectively, 14-59 days after vaccination, and VE decreased with time since vaccination with no remaining protection at 180-365 days after vaccination.
CONCLUSION
Adapted XBB.1.5 vaccine provided moderate protection within 120 days after vaccination against severe COVID-19 outcomes among ICPs aged ≥18 years during a period with BA.2.86/JN.1 replacing the XBB.1.5 variant.
A. Blake, J. Humphreys, K. Olson et al.· Expert Review of Vaccines· 0 citations
Background: Within the VEBIS-EHR project, monthly vaccine effectiveness (VE) of COVID-19 vaccines is routinely estimated across EU/EEA countries. While VE quantifies direct protection, it does not capture the overall population benefit of vaccination campaigns in terms of severe outcomes prevented. Aim: To estimate the impact of the 2023 and 2024 autumn COVID-19 vaccination campaigns in adults aged [≥]65 years. Methods: We conducted a retrospective cohort study using electronic health records data from Belgium, Denmark, Italy, Navarre (Spain), Portugal, Norway and Sweden. Weekly numbers of averted COVID-19-related hospitalisations and deaths during the 12 months following each campaign were estimated using observed COVID-19-related events, vaccine coverage (VC) and interpolated weekly VE. Results: Across participating countries/regions, among adults aged [≥]65 years, the 2023 autumn vaccination campaign averted approximately 6,200 hospitalisations (prevented fraction [PF] 10%) compared with 2,200 (PF 12%) in 2024. Among those aged [≥]80 years, the number of averted COVID-19-related deaths was 811 (PF 13%) for the 2023 campaign and 156 (PF 12%) for the 2024 campaign. Impact varied across countries, reflecting differences in VC, vaccination timing and outcome occurrence. Conclusion: The 2023 and 2024 autumn vaccination campaigns resulted in substantially different numbers of averted COVID-19-related hospitalisations and deaths among older adults, with fewer events averted in 2024. These findings highlight that the impact of vaccination programmes depends not only on VC and VE but also on alignment between vaccination timing and periods of increased viral circulation.
Y. Mansiaux, A. Blake, N. Nicolay et al.· medRxiv· 0 citations
