The specialist in infectious diseases WHO Maria Van Kerkhove
June 9, 2020 14h10
Updated at 15h33
COVID-19: the WHO made a controversial statement on the asymptomatic, then retracts
The statement of a leader of the world health Organization (WHO) to the effect that asymptomatic individuals do not receive that very rarely the SARS-CoV-2 has raised some eyebrows with several experts, who believe that such an assertion, premature, because not (yet) supported by the science, it sends a “strange message” to the public. Before the wave of criticism, WHO had to admit on Tuesday that the rate of transmission of the virus through asymptomatic to this day, remains unknown.
During a press conference of the WHO, on Monday, the infectious disease specialist Maria Van Kerkhove said that the data currently available suggested that asymptomatic individuals would provide very little COVID-19.
Experts were quickly called into question this statement, especially that a study published not later than June 3, in The Annal of Internal Medicine suggests that approximately 40% to 45% of cases of COVID-19 do not show symptoms, but they can still pass the disease in a proportion yet to be determined. The research had already demonstrated that people pre-symptomatic could transmit the virus before developing symptoms.
“This goes against all my impressions of the science to date suggest that persons with asymptomatic and pre-symptomatic are an important source of infection to others”, he responded to a professor of the London School of Hygiene and Tropical Medicine, Liam Smeeth, whose remarks were broadcast on the website of the Science Media Centre.
The declaration of Dr. Van Kerkhove has also surprised the Dr Guy Boivin, of the Department of microbiology-immunology and infectiology, Faculty of medicine of Laval University. In an interview to the Sun on Tuesday morning, he first reminded that “it is not everyone who has the virus and who has a fever or has symptoms very obvious”.
“Sometimes, what we classed as asymptomatic were more likely than pre-symptomatic because they have developed symptoms a few days after,” says the virologist, who also notes that “the case that is said to be asymptomatic may be asymptomatic than that.” “When we search in more detail, we can see that they have symptoms and that they should not be categorised as asymptomatic.”
However, Dr. Guy Boivin agrees that symptomatic individuals are typically more contagious. “It goes with the viral load. There are more viruses in the secretions, so that if you cough, we excrete more of the virus,” he recalls.
So far, Dr. Boivin, who estimates that between 30% and 60% of cases of infection with the SARS-CoV-2 would be asymptomatic – “we have seen specific cases of infection in pregnant women who could be asymptomatic in a proportion of 60%”, is not willing to say that the case of transmission by these asymptomatic are “rare”.
“I think it is premature as the message. It requires more data, documentation, and it sends the wrong public health message. It suggests that if you are asymptomatic, you don’t need to put on a mask because you don’t transmit the virus”, says Dr. Boivin.
The infectious disease specialist recalls in this respect that the genital herpes virus, although a virus is completely different from SARS-CoV-2 is transmitted more easily when the infected person shows symptoms, but that person may also shed the virus and transmit it is asymptomatic.
During a session of questions and answers on the COVID-19 held by the WHO on Tuesday, Dr. Van Kerkhove has clarified his remarks by acknowledging that the science has not yet determined how often the asymptomatic cases could transmit the COVID-19.