WHO epidemiologist says transmission from asymptomatic cases of Covid-19 is “very rare”

World Health Organisation epidemiologist Maria van Kerkhove on Tuesday clarified her comments that transmission from symptomatic cases of Covid-19 was "very rare", citing a "misunderstanding".

Maria Van Kerkhove, the World Health Organisation's Covid-19 technical lead, had said that on the basis of studies carried out in several countries, the transmission of the virus by an asymptomatic person seemed "very rare".

At a virtual press conference on Monday, citing the example of Singapore Kerkhove had said that at least half of Singapore's newly discovered coronavirus cases were asymptomatic.

"We have a number of reports from countries who are doing very detailed contact tracing. They're following asymptomatic cases, they're following contacts and they're not finding secondary transmission onward. It's very rare," she had said as quoted by Reuters .

The comment had sparked multiple debates with experts across the globe questioning the scientific basis of this conclusion that transmission from asymptomatic cases was “rare.”

She later clarified this comment stating that she wanted to clarify a “misunderstanding” and that she had only been referring to a “subset of studies.”

During a discussion rebroadcast Tuesday on the WHO's Twitter account, Van Kerkhove said she wanted to clarify a misunderstanding.

"I was referring to very few studies, some two or three", she had said during a discussion posted on WHO’s official Twitter account.

"I was not stating a policy of WHO," she said.

"I used the phrase 'very rare', and I think that is a misunderstanding to state that asymptomatic transmission globally is very rare. What I was referring to was the subset of studies," she further said.

Kerkhove later posted a summary of Covid-19 transmission from the WHO citing the conclusion regarding asymptomatic cases.

“@WHO recently published a summary of transmission of #COVID19, incl. symptomatic, pre-symptomatic and asymptomatic transmission,” Kerkhove wrote on Twitter.

“In this summary, we state, "Comprehensive studies on transmission from asymptomatic individuals are difficult to conduct, but the available evidence from contact tracing reported by Member States suggests that asymptomatically-infected individuals are much less likely to transmit the virus than those who develop symptoms,” she tweeted.

“In these data, it is impt to breakdown truly asymptomatic vs pre-symptomatic vs mildly symptomatic. Also to note that the percentage reported or estimated to be "asymptomatic" is not the same as the % that are asymptomatic that actually transmit,” she added.