WHO Walks Back Statement That Asymptomatic Coronavirus Transmission Is ‘Very Rare,’ Now Says It Could Be ‘Around 40%’


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The World Health Organization (WHO) walked back a statement made yesterday that asymptomatic transmission is “very rare,” saying at a press conference Tuesday morning that some estimates show asymptomatic transmission rate could be as high as 40%. 

The organization’s technical lead for COVID-19, Maria Van Kerkhov, said at a press conference Monday that it’s ‘very rare’ for patients who have coronavirus without showing any symptoms to transmit the virus to another person. 

“From the data we have, it still seems to be rare that an asymptomatic person actually transmits onward to a secondary individual,” she said Monday according to CNBC

Tuesday morning, the WHO said at a press conference that some estimates show that “around 40%” of transmission may be due to asymptomatic transmission. 

“To truly understand how many people don’t have symptoms, we don’t actually have that answer yet,” Van Kerkhov said. “There are some estimates that suggest that anywhere between 6% of the population and 41% of the population” have coronavirus but don’t have symptoms. 

“What we need to better understand is how many of the people in the population don’t have symptoms, and separately, how many of those individuals go on to transmit to others.”

She said that yesterday, she was referring to “2 or 3 studies” that tried to follow asymptomatic cases. (RELATED: China Suppressed The Truth About Coronavirus. Top WHO Officials Keep Praising China’s ‘Transparency’)

“That’s a very small subset of studies,” she said. “I was responding to a question at the press conference, I wasn’t stating a policy of WHO or anything like that, I was just trying to articulate what we know.” 

Van Kerkhov said that it is “misunderstanding to state that asymptomatic transmission globally is very rare.”

“What I didn’t report yesterday,” she said, is that “some modeling groups have tried to estimate what is the proportion of asymptomatic people that may transmit.”

There is a “big range” of estimates from different models, she added, “but some estimates of around 40% of transmissions may be due to asymptomatic transmission.”

Former Obama administration health care head Andy Slavitt said on Twitter Tuesday that “much more humility & care should be expected from the WHO.”

Slavitt took issue with the WHO’s Monday statement calling asymptomatic transmission “very rare,” saying Monday that he believes it was “an irresponsible statement even though it was based on legitimate observations.”

The former Obama administration official wrote on Twitter Monday that he discussed the WHO statement with scientists and that they were surprised the organization would claim that asymptomatic transmission is rare. The scientists pointed out, according to Slavitt, that there are very few studies on the issue and that there is a degree of uncertainty.