NASHVILLE, TN (WGNS) Middle Tennessee has lived through enough COVID waves to know the numbers tell the story, and the latest national tally from the CDC is a sobering one. Between 380,000 and 540,000 people across the country were hospitalized during the 2024–2025 season, and as many as 63,000 died. It’s the kind of data that reminds clinicians why they keep studying how well each new vaccine holds up against a virus that never stops changing.

That’s where Vanderbilt Health comes in. As the coordinating center for the IVY Network — a 26‑hospital research collaboration spread across 20 states — Vanderbilt helped lead a new case‑control study that looked at how the 2024–2025 COVID vaccine performed in real‑world hospital settings. The results, published this month in JAMA Network Open, are encouraging.

Adults who received the updated vaccine and were not immunosuppressed were 40% less likely to be hospitalized with COVID‑related illness. Even more striking, they were 79% less likely to require a ventilator or die. Researchers say that difference is exactly what they hope to see when evaluating a vaccine’s ability to prevent the worst outcomes.

Wesley Self, MD, MPH — Vanderbilt’s Senior Vice President for Clinical Research and the principal investigator for the IVY Network — put it plainly: a vaccine’s power to prevent critical illness and death is one of the most important measures of its value. Despite the virus’s constant evolution, he said, last year’s U.S. vaccines “were highly effective at preventing critical illness and death.”

The study followed 8,493 adults admitted with acute respiratory illness between September 1, 2024, and April 30, 2025. Nearly 1,900 of them had confirmed COVID. Among patients whose immune systems weren’t suppressed by cancer treatments or transplant medications, the vaccine offered protection across multiple circulating strains.