On Monday, Maria Van Kerkhove, the World Health Organization technical lead on covid-19, stunned public health officials worldwide when she said during a briefing in Geneva that “it still seems to be rare that an asymptomatic person actually transmits onward to a secondary individual.” The next day, Van Kerkhove and WHO rushed to clarify that much remains unknown about the role of asymptomatic transmission of the virus.

That is true enough, but the answers are slowly emerging. Evidence is accumulating, though it remains inconclusive, that the novel coronavirus can indeed spread silently, transmitted through infected people who will never experience symptoms, just as it is transmitted by the presymptomatic before they become ill. Covid-19’s dual nature — often benign, yet sometimes deadly — puts it in a rare category among the common pathogens that afflict humanity.

Read the full op-ed on The Washington Post website.