I’ve been exposed to Covid-19. When should I get tested?

For purposes of contact tracing in the U.S., an “exposure” to COVID-19 involves having spent more than 10 minutes at less than 6 feet from someone who is infected while wearing no personal protection, says Ilhem Messaoudi, a viral immunologist at the University of California, Irvine. “When contact tracers go around and assess risk, that’s the kind of question they’ll ask: Where were you, how long did you interact, were you wearing a mask?” she says.