A scientist from the World Health Organisation (WHO) Monday said that asymptomatic transmission of coronavirus was not a significant factor in the spread of the virus, leaving experts confused, the New York Times reported.
Globally, over 7 million people have been infected with the virus, and more than 4,00,000 have died due to the disease.
Dr Maria Van Kerkhove, the WHO’s technical lead for Covid-19 said, “It still appears to be rare that an asymptomatic individual actually transmits onward.” She further said that governments should instead focus more attention on controlling the spread among people with symptoms.
“We have a number of reports from countries who are doing very detailed contact tracing,”, she said, adding, “They are following asymptomatic cases, they are following contacts, and they are not finding secondary transmission onward. It is very rare. Much of that is not published in the literature.”
“That fundamentally changes our understanding of how this virus is spread and what we should do as a response,” said Dr. Ashish Jha, the director of Harvard’s Global Health Institute. “This is not a minor, technical clarification. The implications of what is being said are very, very substantial, and it requires a lot more context and explanation than WHO is providing right now.”
Later on Monday, Dr Maria cited a WHO report from June 5, which said that based on evidence from contact tracing, “asymptomatically infected individuals are much less likely to transmit the virus than those who develop symptoms.”
Dr Jha also said that a finding of this magnitude, if true, should not have been casually been revealed in the middle of an hour-long news conference. It deserved an entire briefing on its own.
“Asymptomatic spread is what makes controlling this disease so incredibly hard,” he said. If that’s not the case, he added, “then that changes the ballgame. It’s too big a finding to be shared in passing.”
A researcher at Boston Children’s Hospital and co-author of a study on asymptomatic transmission, Dr Avantika Singh said that an infected person is most likely to spread the virus in the few days prior to the onset of symptoms. She said she was “highly curious” to hear more from the WHO, and to see the evidence behind Dr Maria’s statements, which seem to contract the commonly held belief.
“We are not commenting specifically on the WHO’s findings because we haven’t seen them,” said Dr Hanalise V Huff, the other author involved in the study. “But given the evidence, it’s pretty convincing that asymptomatic and pre-symptomatic spread exists.”