Last year’s 2025–26 Covid-19 vaccines reduced the odds that an adult would require Covid-related emergency or hospital care by about 50%, according to a new peer-reviewed study.
Widespread Data Sources
The study, Interim Estimated Effectiveness of 2025-2026 COVID-19 Vaccines in Adults Using a Test-Negative Design, was just published June 23 in JAMA Network Open. The analysis included almost 86,000 emergency department and urgent care visits for acute Covid-like illness, along with about 26,000 hospitalizations for similar illnesses.
The large-scale data collection was performed by the VISION network of health care systems including 253 emergency departments and urgent care centers and 179 hospitals in 7 states.
Covid Vaccine Effectiveness 50–53%
Patients’ histories of Covid vaccination and prior infections were documented along with current diagnostic tests. That made it possible to estimate vaccine effectiveness by comparing how often vaccinated and unvaccinated patients with similar symptoms tested positive for Covid-19 during their encounters.
The results showed vaccine effectiveness of about 50–53%. The benefit was seen even among people who had previously been vaccinated or had prior Covid infection.
This, incidentally, was the study originally scheduled for publication in the CDC’s Morbidity and Mortality Weekly Report (MMWR) but was delayed by the acting CDC director, Dr. Jay Bhattacharya, because of his methodological concerns.
Implications for You
The Covid-19 vaccines work to protect you against severe disease. When we get to this fall (I hope not too soon), get your 2026–27 vaccine. It’s the right decision.