The spread of more contagious Covid-19 variants has renewed questions about outdoor transmission risk. | Getty Images

What to know about your risk among friends, runners, and passersby outside.

There have been some bright spots recently in the fight against Covid-19: Infection rates are dropping in most states, more and more Americans are becoming eligible for vaccination, and the Food and Drug Administration now says the Johnson & Johnson vaccine meets the requirements for emergency use authorization. Meanwhile, new research finds that the Pfizer and Moderna vaccines are not only effective at preventing illness, hospitalization, and death, but they’re probably quite effective at preventing transmission, too.

But the optimism is tempered somewhat by the spread of more contagious Covid-19 variants, like B.1.1.7 and 501Y.V2, initially discovered in the UK and South Africa, respectively. Experts say the B.1.1.7 variant could be dominant