COVID-19 Boosters Reduce Hospitalizations and Deaths by Up to 64% in Large Veterans Study
核心洞察
A large study of nearly 300,000 U.S. military veterans found that 2024-2025 COVID-19 (搜索) mRNA boosters reduced emergency department visits by 29%, hospitalizations by 39%, and deaths by 64% compared to unvaccinated individuals.
The protective effects were observed across all age groups and in people with or without major chronic medical conditions, challenging the notion that younger, healthier individuals don't need vaccination.
Despite waning effectiveness compared to initial vaccines, the study published in The New England Journal of Medicine demonstrates continued meaningful clinical benefit from annual COVID boosters even in populations with prior immunity.
A comprehensive study of nearly 300,000 U.S. military veterans has demonstrated that last year's COVID-19 (搜索) booster vaccines significantly reduced severe outcomes, including a 64% decrease in deaths, even among populations with substantial prior immunity from previous infections and vaccinations.
The research, published Wednesday in The New England Journal of Medicine, tracked 164,132 veterans who received both a 2024-2025 COVID booster and flu shot, compared with 131,839 who received only the flu vaccine. Over six months, veterans who received the COVID vaccination experienced a 29% decrease in emergency department visits, a 39% decrease in hospitalizations, and a 64% decrease in deaths.
Effectiveness Across All Demographics
The protective effects remained consistent regardless of age or the presence of major chronic medical conditions. Of the study participants, 35% received the Pfizer vaccine (COMIRNATY) and 64% received the Moderna vaccine (Spikevax). The vast majority of participants were at least 45 years old, and virtually all who received a COVID shot got one of the two approved mRNA-based vaccines.
"The vaccines are still providing additional, not perfect, protection against meaningful outcomes, including hospitalization and death, even though such severe outcomes are now much less common overall than early in the pandemic," said Dr. Jesse Goodman of Georgetown Medical Center, who was not involved in the study.
Clinical Impact in Context
In absolute terms, vaccination resulted in 18.3 fewer emergency department visits, 7.5 fewer hospitalizations, and 2.2 fewer deaths per 10,000 patients. While these numbers appear modest, researchers noted that the smaller absolute impact reflects the milder nature of currently circulating virus variants and the accumulated immunity from previous infections and vaccinations.
The COVID vaccines' effectiveness against symptomatic disease has generally waned since their initial deployment, with the 2024-2025 shots offering 29 to 64% protection compared with the 94% protection provided by vaccines in 2019. However, this decline is expected in populations with some prior immunity, according to Stanley Perlman, a coronavirus researcher at the University of Iowa.
Implications for Vaccination Policy
The findings challenge current assumptions about vaccination needs across different populations. "The research calls into question the idea that younger individuals and those without risk factors don't need the vaccine," said Nisha Viswanathan, medical director of the UCLA Long COVID program. "While the shot is most effective for older individuals and those with comorbidities, it was also protective in those without risk factors."
The Centers for Disease Control and Prevention currently recommends this year's COVID shots to adults aged 65 and older and those with underlying health conditions, while vaccination for healthy people older than six months should be based on shared clinical decision-making.
Current Season Relevance
Despite examining last year's vaccines, researchers believe the findings remain relevant for the current season. The virus that circulated last year derives from the same precursor virus (JN.1 (搜索)) as current variants, with similar severity profiles. Both 2025-2026 mRNA vaccines (搜索) target the LP.8.1 variant (搜索), with COMIRNATY showing a fourfold increase in neutralizing antibody titers and Spikevax demonstrating an eightfold increase above baseline levels.
Dr. Eric Rubin, NEJM editor-in-chief, noted that "given what we know about the risk of vaccination in this middle-age and older population, which is extremely low, these data suggest that vaccination remained an attractive option."
Vaccination Uptake Challenges
Only 21% of the adult U.S. population received COVID vaccination last year—a proportion that has been steadily declining. With reduced vaccine-induced immunity across the population, researchers suggest that more people "would benefit even more from getting vaccinated this year."
The study authors acknowledged that as an observational study rather than a randomized trial, the research cannot definitively prove causation, though the findings align with previous observational studies supporting meaningful vaccine effectiveness against significant outcomes.