There have been a number of recent reports of fully vaccinated people testing positive for the coronavirus — at the White House, Congress, the Olympics and Major League Baseball. And with the fast-spreading delta variant driving up infections, hospitalizations and deaths, a lot of people are wondering whether the vaccines are as protective as we thought.
But the current crop of vaccine breakthrough cases doesn't surprise or alarm public health experts. "I haven't seen any signals in the U.S. indicating that they are occurring at the levels that would give us concern that the [vaccine] effectiveness is going down," said Saad Omer, director of the Yale Institute for Global Health.
In all of these settings, from Capitol Hill to professional sports, nearly everyone is vaccinated, he points out, and people are subject to frequent, asymptomatic testing. "It is not surprising to see a substantial number of cases in the vaccinated when the vaccination rate is high," he said.
Still, people who've been vaccinated may rightly be asking: Are breakthrough cases becoming more common because of the delta variant? Could I get sick or get a family member sick?
Here's what to know about breakthrough cases in the context of the delta variant, and what scientists are doing to track the vaccines' efficacy.