A top official of the World Health Organization has retracted her statements on the transmission of the novel coronavirus of asymptomatic cases, saying that it is very rare for them to transmit the virus. Her comment sparked a new debate among infectious-disease experts about the risks of silent spreads of COVID-19, CBC News reported.
Earlier this year, the health agency had said that it did not see asymptomatic cases as a major cause of viral spread. But Van Kerkhove's remark at a press conference on Monday has revived the controversy over the virus's transmission routes.
She said at a media briefing on Monday, that "from the data we have, it still seems to be rare that an asymptomatic person actually transmits onward to a secondary individual. It's very rare."
But on Tuesday, she aimed to clear up the "misunderstandings" about those statements in an updated briefing. She emphasized that she was referring to the "very few studies" that tried to follow asymptomatic carriers to know how they could infect other people.
She clarified that she was only responding to a question at the press conference and not stating a policy of the health agency. She added that she did not intend to imply that asymptomatic transmission of the virus is rare across the globe. Instead, the available data has not clarified the extent to which asymptomatic cases infect other people.
Bad Communication from WHO
Ever since the pandemic began, there has been confusion over the evolving science on the amount of asymptomatic transmission, said Dr. Isaac Bogoch, an infectious disease physician at Toronto General Hospital.
"At a fundamental level, it's extremely important to explain the science well and explain what our current knowledge is and explain what the unknown questions are," Bogoch said.
However, the WHO did not seem to have done an excellent job of communicating yesterday and even did a questionable job of it today when trying to clarify their comments.
Bogoch also said that studying the true amount of asymptomatic carriers of COVID-19 is exceptionally challenging because of the key discrepancies between people who have no symptoms. They could be presymptomatic and those who are subclinical with less severe symptoms.
So, when WHO announced that asymptomatic people rarely transmit the virus, it is met with backlash as there are different types of people without symptoms. It is a little complicated than the health agency had reported.
Van Kerkhove's statement showed how people quickly are desperate for clear information that should be provided by them. More than ever, people need the WHO to be a trusted voice in these times.
Flawed Data on the Asymptomatic Spread
It is not uncommon for infected people to not show any symptoms, said some experts. For instance, in a non-peer-reviewed study from Germany in May based on 919 people in Heinsberg, experts have found that about one in five of those infected were symptomless.
But there is only a limited amount of information on how people without symptoms can transmit the disease. In Singapore, there had been asymptomatic transmission cases between people living in close quarters. While in China, 300 asymptomatic COVID-19 carriers in Wuhan were not infectious.
Experts agree that it is challenging to study asymptomatic transmission. The one that Van Kerkhove was referencing was a modeling data that estimated anywhere between 6% and 41% of the population might be asymptomatic cases. However, that modeling data is "flawed" because it assumes the number of asymptomatic cases then runs a simulation on how people could then transmit it.
"Asymptomatic spread is a dumpster fire in terms of data," said Dr. Lynora Saxinger, an infectious disease physician at the University of Alberta
