Lab accidents have happened in the past. But scientists say it is extremely rare for viruses to be leaked from facilities designed to handle deadly pathogens.
The northeastern city of Harbin thought it could breathe a sigh of relief, but then a new spike of cases appeared. Public health experts say its experience is likely to be repeated elsewhere.
The city where Covid-19 first emerged suffered more than anywhere in China. But on Sunday the last patients treated for the disease were able to leave the hospital.
Concerns are rising that African nations have stopped providing care and prevention for other deadly diseases as it shifts its resources toward fighting Covid-19.
Governments are testing people for coronavirus antibodies to estimate how many people have contracted, and recovered, from the disease. But scientists say the accuracy of the tests remains a question.
Two California residents who died in early February tested positive for the coronavirus postmortem. The discovery proves the virus was spreading throughout the US far earlier than previously thought.
A different diagnostic standard would have at least quadrupled the number of confirmed Covid-19 patients in China, researchers from Hong Kong said in a study published in The Lancet.