Updated COVID-19 vaccine cut hospitalization risk by 35% in 2024-2025 season

Adults who received the 2024-2025 formulation of the COVID-19 vaccine had substantially lower odds of medically attended COVID-19, including a 35% reduction in hospitalization risk, according to a study published in JAMA Internal Medicine.

The researchers, including Ryan E. Wiegand, Ph.D., from the National Center for Immunization and Respiratory Diseases at the Centers for Disease Control and Prevention, analyzed patient encounters with a COVID-19-like illness diagnosis and a SARS-CoV-2 molecular or antigen test performed within a window of 10 days before to 3 days after the encounter, occurring between September 5, 2024, and September 2, 2025. The exposure of interest was vaccination with the 2024-2025 COVID-19 vaccine formulation, approved by the FDA in August 2024, administered 7 to 299 days before the encounter.

Their findings were drawn from the VISION network, a multisite, electronic medical record-based surveillance system spanning 381 emergency department/urgent care sites and 246 hospitals across six states. This network design allows researchers to capture a large, geographically diverse sample of clinical encounters in near real time, which is particularly useful for monitoring vaccine performance against a virus whose circulating variants and population immunity landscape continue to shift from season to season.

Among 333,262 eligible emergency care encounters and 97,663 hospitalizations in immunocompetent adults 18 years and older, estimated vaccine effectiveness was 26% against emergency department/urgent care (ED/urgent care) visits, 35% against hospitalization and 41% against critical illness.

Effectiveness estimates were similar in adults 65 and older, with 26% protection against ED/urgent care encounters, 35% against hospitalization, and 41% against critical illness in that subgroup. Clinically, this indicates the vaccine's relative benefit held up in the age group at highest baseline risk for severe outcomes, a population in whom waning immunity and accumulating comorbidities often complicate efforts to demonstrate consistent protection across health care settings.

Among immunocompromised adults, vaccine effectiveness against hospitalization was lower, at 24%, based on 32,629 hospitalizations.

Waning protection was a consistent pattern across all groups. Vaccine effectiveness was higher in the 7 to 59-day window after vaccination and declined with increasing time since vaccination. The study abstract does not report specific numeric effectiveness values for the early (7 to 59 day) window separately from the overall 7 to 299-day estimates, so the exact magnitude of waning cannot be quantified from available information. This pattern mirrors waning trends documented with earlier COVID-19 vaccine formulations and may factor into future discussions about optimal timing of annual vaccination relative to anticipated periods of peak respiratory virus circulation.

“In this test-negative case-control study, 2024-2025 COVID-19 vaccination was associated with additional protection against COVID-19–associated outcomes for immunocompetent adults, older adults, and immunocompromised adults, highlighting the benefits for people to obtain recommended COVID-19 vaccinations,” Wiegand and his team write in the study. “For practicing clinicians, these results affirm that annual COVID-19 vaccination continues to meaningfully reduce the risk of severe outcomes, especially in the first 6 months after vaccination and among patients at highest risk.”