Key Points:
- COVID vaccine effectiveness lowers severe illness, hospitalization, and death.
- Protects all ages and those with chronic conditions.
- Remains a safe, effective option.
A large U.S. study found that updated COVID-19 vaccines from Moderna and Pfizer/BioNTech significantly reduced severe illness, hospitalizations, and deaths among vaccinated individuals last year, demonstrating ongoing COVID vaccine effectiveness. The findings, published Wednesday in The New England Journal of Medicine, are based on data from more than 295,000 U.S. military veterans.
Researchers compared 164,132 veterans who received both the 2024–2025 COVID booster and a flu shot with 131,839 who received only the flu vaccine. Most participants were at least 45 years old, and nearly all vaccinated individuals received one of the two authorized mRNA-based boosters.
Over a six-month period, those who received both shots were 29% less likely to visit the emergency department, 39% less likely to be hospitalized, and 64% less likely to die compared with those who only received the flu shot.
Study tracks military veterans
The study found consistent benefits across all age groups and among individuals with chronic conditions. Although the added benefit was modest, researchers said the data demonstrated that COVID vaccination continues to provide meaningful protection even as severe outcomes have become less common, reinforcing ongoing COVID vaccine effectiveness.
In practical terms, vaccination was associated with 18.3 fewer emergency visits, 7.5 fewer hospitalizations, and 2.2 fewer deaths per 10,000 people.
Dr. Jesse Goodman, a professor at Georgetown University Medical Center who was not involved in the research, said the results show that COVID vaccines “are still providing additional, not perfect, protection against meaningful outcomes, including hospitalization and death.”
Protection remains meaningful
Dr. Eric Rubin, editor-in-chief of The New England Journal of Medicine, noted that the absolute benefit of vaccination has declined as the virus has evolved and as overall immunity in the population has increased. “Given what we know about the risk of vaccination in this middle-aged and older population, which is extremely low, these data suggest that vaccination remains an attractive option,” Rubin said.
Vaccine effectiveness appeared to decline slightly over the six-month study period, consistent with previous findings that protection wanes over time. Nevertheless, these results emphasize ongoing COVID vaccine effectiveness in preventing severe outcomes.
Goodman, a former chief scientist at the U.S. Food and Drug Administration, said that multiple recent studies—including this one—continue to support the effectiveness of updated vaccines in preventing serious outcomes.
The researchers acknowledged that because the study was observational rather than randomized, it cannot conclusively prove that vaccination caused the reduced rates of hospitalization or death. However, they said the evidence aligns with broader public health data showing that vaccination reduces the severity of COVID-19 infections, underlining the COVID vaccine effectiveness across populations.
The study comes as health officials prepare to distribute updated COVID vaccines for the 2025–2026 season, aiming to maintain protection against emerging variants and prevent a rise in severe cases among vulnerable populations.
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