Vaccines Ward Off Severe Covid in U.S., Wane Against Infections

Covid-19 vaccines remain highly effective at keeping people alive and out of the hospital, but new U.S. data add further support to the argument that the shots aren’t preventing infections as much as they once did.

Unvaccinated people were about five times more likely to test positive for the virus than the vaccinated in the week starting Sept. 26, down from about 15 times more likely in May, according to the latest age-adjusted data from the Centers for Disease Control and Prevention, which were updated Monday.

The new figures come shortly after the CDC approved booster shots for ...