Once infected with the coronavirus, are you very contagious BEFORE you notice any symptoms?
Evidence has steadily accumulated since the spread of COVID-19 began that people infected by the coronavirus don't show symptoms for days, so can be highly infectious without being aware of it. This has made controlling the virus' spread much more difficult than some past respiratory infections such as ordinary influenza or the 2003 SARS virus.
The difficulty of detecting asymptomatic infection has led to stronger recommendations from public-health authorities to wear face coverings in public settings, and to calls by public-health advisors and specialists to increase testing across the population. "This unprecedented pandemic calls for unprecedented measures to achieve its ultimate defeat," the New England Journal of Medicine said in an April editorial.
