You go out to a bar with friends this week, and you’re planning to visit your elderly relatives in a few days. You feel healthy, and you even get a COVID-19 test out of caution. The result comes back negative. Is it safe to go?

Not exactly, experts say. How well COVID-19 tests work in people who feel healthy is still a key unknown of the pandemic. The test may overlook the small but growing amounts of virus in someone who has not yet developed symptoms, who could still go on to spread COVID-19 without knowing it. So as Americans weigh the risks of attending protests, rallies, birthday parties, dinners, and all the social gatherings that make up normal life, they will have to contend…