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Study Affirms COVID-19 Booster Effectiveness Against Hospitalization and Death

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New Study Reinforces COVID-19 Booster Effectiveness Against Severe Outcomes

A new study, involving over 3 million adults in England who received the autumn 2022 COVID-19 vaccine, indicates that booster vaccines reduced the risk of COVID-19-related hospitalisation and death. The research, conducted by the universities of Bristol and Oxford, provides further evidence of booster vaccination's effectiveness.

Booster vaccines approximately halved the risks of COVID-19 hospitalisation and death.

The study, published in Vaccine, found similar effectiveness for Moderna (BA.1 mRNA-1273) and Pfizer-BioNTech (BA.1 BNT162b2) booster vaccines, though protection decreased over time.

Study Design and Participants

Researchers investigated the impact of booster vaccines administered during the autumn 2022 campaign in England. The focus was on previously vaccinated individuals aged 50 or over.

The study meticulously analyzed linked GP and hospital records from the OpenSAFELY research platform. It compared 3,464,877 adults eligible for booster vaccination with an equal number of unvaccinated individuals. Participants were carefully matched based on age, last COVID-19 vaccine dose date, prior vaccination brand, clinical vulnerability, and geographical region. They were then monitored for nearly a year to track COVID-19 hospitalisation and death events.

Key Findings on Hospitalisation and Death

Over 2.5 million people were followed for a year, during which the study recorded 14,436 COVID-19 hospitalisations and 1,152 COVID-19 deaths.

Boosted individuals showed significantly lower 350-day risks for both outcomes:

  • COVID-19 hospitalisation: 3.78 per 1,000 for boosted vs. 6.81 per 1,000 for unvaccinated.
  • COVID-19 death: 0.29 per 1,000 for boosted vs. 0.61 per 1,000 for unvaccinated.

Booster vaccines approximately halved the risks of COVID-19 hospitalisation and death. The strongest protection was observed in the first 70 days following vaccination.

Vaccine Performance and Protection Duration

Both Moderna and Pfizer-BioNTech boosters performed similarly for COVID-19 outcomes, demonstrating comparable effectiveness in reducing severe illness and mortality. While initial protection was strong, the study noted that this protection decreased over time.

Addressing Potential Confounders

Interestingly, a small reduction in fracture risk was also noted for boosted individuals. This outcome is not expected to be causally related to the vaccine. This finding suggests that while some confounders might not have been fully accounted for, the minimal effect on fractures supports the validity of the study's primary conclusions regarding COVID-19 outcomes.

Expert Commentary

Dr. Paul Madley-Dowd, a Research Fellow at the University of Bristol and corresponding author, stated that the findings reinforce the importance of booster vaccination against COVID-19 among people over 50 years old. He confirmed that booster vaccinations effectively reduced the risk of hospitalisation and death.