Vaccines are highly effective at preventing Covid-19—but "breakthrough" infections do occur. Here's what to do if you test positive after being fully vaccinated, according to CDC and other experts, Johnny Diaz writes for the New York Times.

When Patrick Doherty learned he had inherited a lethal disease called transthyretin amyloidosis, he enrolled in a trial using CRISPR to treat the condition. The treatment helped stop his symptoms, marking what experts are calling a breakthrough for the gene-editing technology.

World Health Organization officials last week said fully vaccinated people should wear face masks to combat the fast-spreading delta coronavirus variant—but CDC Director Rochelle Walensky on Wednesday said fully vaccinated Americans are "safe" and don't need masks. Here's the latest on the clashing guidance, and how several independent experts are approaching mask-wearing.

Why some vaccinated athletes are testing positive for the coronavirus, how a genealogy database helped crack a 14-year-old cold case, and more in our staff picks for the long weekend.

The California legislature approved a budget deal that will expand Medicaid benefits to 235,000 undocumented immigrants, in today's bite-sized hospital and health industry news from California, the District of Columbia, and Florida.