A medical worker gives a nucleic acid test to an incoming passenger in Shanghai on March 19
Authorities believe a person confirmed Thursday with a new local case of Covid-19 may have been infected by an asymptomatic traveler on a flight from Beijing to Hangzhou, spotlighting the challenges China faces from imported cases and spreading by people with no symptoms.
A doctor writes words of encouragement in a notebook for a patient
Asymptomatic infections have become a new focus in China’s fight against the pandemic, since such people often still move about in society with the potential to spread the virus. China is also grappling with a steady stream of people returning to the country from abroad, many of them Chinese students and other citizens coming home as situations worsen in their host countries.