Washington Post After the Centers for Disease Control and Prevention shifted its coronavirus vaccine guidance from a near-universal recommendation to a more limited approach, many readers asked what has changed in the science to warrant the change. Some wondered how effective boosters really are and whether they should continue receiving them once a year. A new study published in JAMA Internal Medicine helps answer these questions. It found that last season’s updated vaccine provides significant protection against covid-19, particularly against severe illness and death. The results reaffirm the benefit of staying current with covid vaccination.
Researchers analyzed data from approximately 1.8 million Americans between August 2024 and April 2025, of whom only about 13 percent received the 2024–2025 coronavirus shot. They evaluated three clinical outcomes related to the disease: infections, emergency department visits and hospitalization or death.