New Study Confirms Annual COVID Vaccines Reduce Severe Disease Risk Across All Ages

A large study published this week in the New England Journal of Medicine offers fresh evidence that annual COVID vaccination works—and works across the board, regardless of how many times someone has been infected or vaccinated before.

Researchers tracked nearly 300,000 Americans who received the 2024–2025 COVID vaccine and measured what happened next. The numbers were straightforward: vaccinated people made 29 percent fewer emergency room visits for COVID, were hospitalized 39 percent less often, and died 64 percent less frequently than their unvaccinated counterparts. About a third of the study participants received Pfizer's vaccine; roughly two-thirds got Moderna's. The protection held steady across every age group examined and among people with and without chronic illnesses.

This finding matters partly because it challenges a narrower view of who needs the shot. The CDC currently recommends annual COVID vaccination for adults 65 and older and for younger people with underlying health conditions. The new data suggest that recommendation may be too limited. Nisha Viswanathan, an internal medicine physician at UCLA who studies long COVID, noted that the study "calls into question the idea that younger individuals and those without risk factors don't need the vaccine." While the vaccine does offer the most protection to older people and those already dealing with other diseases, she said, the evidence shows it also protected healthier, younger people—a detail that matters when deciding who should roll up their sleeve.

Scientists expected vaccine effectiveness to decline over time, and it has. The 2024–2025 shots offered 29 to 64 percent protection against symptomatic infection, a step down from the 94 percent the original vaccines provided in 2019. But that decline is normal, according to Stanley Perlman, a coronavirus researcher at the University of Iowa. As more people encounter the virus through infection or prior vaccination, their immune systems change, and vaccines naturally perform differently in a population with existing immunity. The virus itself has also evolved. Last year's vaccines and this year's both target variants descended from a single precursor strain called JN.1, and the two are similar enough in severity that researchers expect the current season's shots to perform much like last year's did.

Manufacturers have already begun testing the 2025–2026 vaccines, which target a newer variant called LP.8.1. Early lab work suggests both Pfizer and Moderna's updated formulas generate strong immune responses. Moderna's version produced an eightfold increase in neutralizing antibodies—the immune system's protective proteins—compared to baseline levels, while Pfizer's showed a fourfold increase. Perlman cautioned that the difference between the two is unlikely to translate into meaningfully better real-world protection for most people, though the higher antibody levels generally signal stronger defense against severe disease.

One striking fact underscores why these findings matter: only 21 percent of American adults received a COVID vaccine last year, a proportion that has been falling steadily. Perlman observed that with fewer people carrying vaccine-induced immunity, more people would benefit from getting vaccinated this season. The study's authors declined to comment on their findings, but the research aligns with what scientists have observed in previous years—that while COVID vaccines may not stop infection entirely, they remain effective at preventing the outcomes that matter most: the ones that land people in hospitals or morgues.