Coronavirus Vietnam: The mysterious resurgence of Covid-19

A more likely possibility, say researchers, is that the virus went undetected during the months where there were no reported cases, potentially being asymptomatically transmitted in the community. Or there could have been an error somewhere along the quarantine process with someone released prematurely. "There's evidence [the virus] was circulating in Da Nang for several weeks before that first case was diagnosed," says Dr Justin Beardsley, a senior lecturer in infectious diseases at the University of...