TOPLINE:

Adults in England aged 50 years or older who received the bivalent BA.1 mRNA booster vaccine during the 2022 autumn campaign had substantially lower risks for COVID-related hospitalisation and death for up to 350 days after vaccination than peers who did not receive the booster.

METHODOLOGY:

• Researchers in England conducted a matched cohort study emulating target trials to estimate the effectiveness of bivalent original/omicron BA.1 mRNA-1273 and bivalent original/omicron BA.1 BNT162b2 booster vaccines against severe COVID outcomes in adults aged 50 years or older during the autumn 2022 rollout.
• They matched 3,464,877 vaccinated participants with an equal number of control participants who had not received the booster dose, using age, date of last COVID vaccine dose, brand of last COVID vaccine, clinical vulnerability status, and region.
• An additional 531,129 participants who received BA.1 mRNA-1273 were matched with an equal number of participants who received BA.1 BNT162b2 on the same day to directly compare the effectiveness of both boosters.
• The primary outcomes were COVID-related hospital admissions and deaths. The study also assessed non-COVID deaths and fractures; fractures served as a negative control because vaccination was not expected to affect them.
• Participants were followed up until September 11, 2023; death; or deregistration from their primary care provider or for up to 350 days after trial initiation, whichever occurred first.

TAKEAWAY:

• Overall, 14,436 COVID-related hospitalisations and 1152 COVID-related deaths were reported in the cohort of matched boosted and unboosted control participants.
• Boosted vs unboosted control participants had roughly half the risk for COVID-related hospitalisation (adjusted hazard ratio [aHR], 0.51; 95% CI, 0.50-0.53) and COVID-related death (aHR, 0.45; 95% CI, 0.40-0.51).
• Protection was greatest soon after receipt of the booster and gradually waned; for COVID-related hospitalisation, vaccine effectiveness declined to about 30% (aHR, 0.7) by 126 days after vaccination, and a similar decline was observed for COVID-related death.
• Booster participants had lower risks for non-COVID death and fractures; no clear difference was observed in the risks for COVID-related hospitalisation or death between recipients of the BA.1 mRNA-1273 and BA.1 BNT162b2 vaccines.

IN PRACTICE:

"This study found substantially lower risks of COVID-related hospitalisation and death, and of non-COVID death, up to 350 days after booster vaccination among adults aged over 50 who received a bivalent original/omicron BA.1 mRNA booster vaccine compared to those who remained unboosted," the authors wrote.

SOURCE:

The study was led by Paul Madley-Dowd, University of Bristol, Bristol, England. It was published online on February 18, 2026, in Vaccine.

LIMITATIONS:

Fracture rates were slightly lower among boosted participants than among unboosted control participants, suggesting unmeasured differences between the groups. Considerable vaccine effectiveness seen immediately after vaccination may also have reflected unmeasured differences. Participants who refused the booster after earlier doses may have differed in their health status from those who received it. 

DISCLOSURES:

This study was supported by multiple sources, including NHS England, the Wellcome Trust, and the Medical Research Council. One author received support from the Medical Research Council Integrative Epidemiology Unit at the University of Bristol. Another author reported employment with Flatiron Health Inc and holding equity or stock in Roche.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.