New results suggest that a live-virus vaccine intended to protect against shingles—a condition caused by reactivation of the varicella-zoster virus, which also causes chickenpox—prevented illness in 67% of people in the first year after vaccination. But after 10 years, the vaccine’s efficacy against shingles, also known as herpes zoster, had declined to 15%. The study used electronic health record data from more than 500 000 adults aged 50 years or older who received the shot between 2007 and 2018 in California.
