Data suggest 29% to 64% efficacy of 2024-25 COVID vaccine against poor outcomes in US veterans
The vaccine was tied to lower risks of the outcomes among all age-groups, regardless of major underlying medical conditions and immune status.
The estimated effectiveness of last year’s COVID-19 vaccine among US veterans was 29% against related emergency department (ED) visits, 39% against related hospitalization, and 64% against death, researchers from the Veterans Affairs (VA) St. Louis Health Care System write in the New England Journal of Medicine.
Published yesterday, the target trial used electronic health records to estimate the effectiveness of the 2024-25 COVID-19 vaccine among 164,132 veterans who received COVID-19 and influenza vaccines on the same day and a comparison group of 131,839 veterans who received the flu vaccine only from September 3 to December 31, 2024.
Most COVID-19 vaccinees received the Moderna mRNA vaccine (64.0%) or the Pfizer/BioNTech mRNA vaccine (35.3%). A total of 74.1% received the high-dose trivalent (three-dose) formulation of the vaccine. Follow-up was 6 months or until a specified outcome occurred.
“Policymakers are asking a key question: do updated COVID-19 vaccines still confer meaningful protection in the current epidemiologic context?” the study authors wrote. “Contemporary evidence of vaccine effectiveness is crucial to inform COVID-19 vaccine policy deliberations for the 2025–2026 season.”
Absolute risk reductions with vaccination small
Six months after COVID-19 vaccination, the estimated vaccine effectiveness (VE) was 29.3% (95% confidence interval [CI], 19.1% to 39.2%) against related ED visits (risk difference per 10,000 people, 18.3), 39.2% (95% CI, 21.6% to 54.5%) against COVID hospitalization (risk difference per 10,000 people, 7.5), and 64.0% (95% CI, 23.0% to 85.8%) against related death (risk difference per 10,000 people, 2.2).
Contemporary evidence of vaccine effectiveness is crucial to inform COVID-19 vaccine policy deliberations for the 2025–2026 season.
COVID-19 VE against a composite of the three outcomes was 28.3% (95% CI, 18.2% to 38.2%), with a risk difference per 10,000 persons of 18.2 and mild waning over 6 months. The vaccine was tied to lower risks of the outcomes among all age-groups (younger than 65 years, 65 to 75, and older than 75), regardless of major underlying medical conditions and immune status.
Vaccine use was tied to an estimated VE against the composite outcome of 37.1% (95% CI, 19.5% to 49.9%) at 1 to 60 days, 32.5% (95% CI, 14.3% to 45.6%) at 61 to 120 days, and 21.4% (95% CI, 0.3% to 37.0%) at 121 to 180 days.
The findings closely reflect those seen in clinical trials and mechanistic studies of the vaccine. “The absolute risk reductions associated with vaccination were small (18.3 emergency department visits, 7.5 hospitalizations, and 2.2 deaths per 10,000 vaccinated persons) and may reflect the decreased baseline severity of contemporary SARS-CoV-2 infection,” the researchers wrote.
Although the Centers for Disease Control and Prevention (CDC) recommends both the COVID-19 and flu vaccines for everyone 6 months and older, COVID vaccination uptake was only 21% in 2024-25, compared with 42% for flu.
“The lower uptake of the COVID-19 vaccine than of the influenza vaccine reflects the interaction of various drivers, including patient-level health and demographic characteristics, risk–benefit perceptions (e.g., perceived risk of COVID-19, concerns about vaccine-related adverse events, and aversion to mRNA vaccines), geography, workplace policies (some employers require the influenza vaccine but not the COVID-19 vaccine), economic context, social and informational environment, and trust,” the authors concluded.
