CDC report: Double-masking can block more than 90 percent of viral particles

Double-masking — specifically, wearing a surgical mask underneath a cloth mask — may provide an extremely high level of protection against the viral particles that cause Covid-19, the Centers for Disease Control and Prevention reported Wednesday.

A year into the pandemic, the report is the first from the CDC that breaks down how well certain mask-wearing techniques work to protect wearers and those around them.

"We know that masks work," said Dr. John Brooks, a medical epidemiologist at the CDC and co-author of the new report. "This is about how...