The World Health Organization walked back a surprise statement that people without symptoms cannot easily spread the novel coronavirus, adding on Tuesday that too much about the virus remains unknown.
“I was responding to a question at the press conference. I wasn’t stating a policy of WHO or anything like that. I was trying to articulate what we know, and in that, I used the phrase ‘very rare.’ And I think that’s a misunderstanding, to state that asymptomatic transmission is very rare,” WHO epidemiologist Dr. Maria Van Kerkhove said Tuesday.
Kerkhove said Monday that “it still seems to be rare that an asymptomatic person actually transmits onward to a secondary individual,” a statement that caused surprise and drew criticism because it would undercut the case for social distancing. The previous understanding of viral transmission had been that people not exhibiting symptoms of the coronavirus are still contagious and should socially distance.
Kerkhove said Tuesday that as much as 40% of viral transmission could be from asymptomatic patients, but too little is understood about the virus to make that conclusion.
“It’s a constant revision and a constant evolution and debate,” Kerkhove said. “And I mean that in a constructive way of saying, ‘What do we know, what are the key questions, what don’t we know, and what are we doing to address those unknown?’ It’s not enough to say we don’t know.”
Kerkhove added that the question of whether people without symptoms are primary transmitters underscores the need for widespread contact tracing and testing. She said guidelines from the WHO to practice social distancing and good hygiene are part of a “comprehensive strategy” to eradicate the virus.