EXPERT REVIEW OF VACCINES · Available online 26 Jul 2026 · In press · DOI 10.1080/14760584.2026.2708184
Alexandre Blake, James Humphreys, Kate Olson, Toon Braeye, Izaak Van Evercooren, Christian Holm Hansen, Ida Rask Moustsen-Helms, Massimo Fabiani, Alberto Mateo-Urdiales, Jesús Castilla, Iván Martínez-Baz, Ausenda Machado, Andre Brito, Rickard Ljung, Nicklas Pihlström, Yohann Mansiaux, Nathalie Nicolay, Susana Monge, Baltazar Nunes, VEBIS-EHR working group
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.
Abstract from DOAJ. Public domain (CC0 1.0).
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Blake, A., Humphreys, J., Olson, K., et al. (2026). Adapted XBB.1.5 vaccine effectiveness against severe COVID-19 outcomes among immunocompromised persons in 2023–24 in six European countries: a VEBIS-EHR network study. EXPERT REVIEW OF VACCINES. https://doi.org/10.1080/14760584.2026.2708184