A top World Health Organization (WHO) expert has tried to clarify "misunderstandings" about comments she made that were widely understood to suggest that people without COVID-19 symptoms rarely transmit the novel coronavirus.
Maria Van Kerkhove, the UN health agency's technical lead on the pandemic, insisted on June 9 that she was referring only to a few studies, not a complete picture, in the comments she made a day earlier.
Van Kerkhove's remarks on June 8 had led to confusion and questions among other experts and health officials who have recommended, and in some places required, that people wear masks to try to prevent the coronavirus from spreading further.
The “clarification” she provided during a WHO social-media chat showed many questions remain about whether infected people who do not show symptoms of illness such as fever, dry cough or difficulty breathing can transmit the virus to others.
Frequently Asked Questions
A vaccine works by mimicking a natural infection. A vaccine not only induces immune response to protect people from any future COVID-19 infection, but also helps quickly build herd immunity to put an end to the pandemic. Herd immunity occurs when a sufficient percentage of a population becomes immune to a disease, making the spread of disease from person to person unlikely. The good news is that SARS-CoV-2 virus has been fairly stable, which increases the viability of a vaccine.
There are broadly four types of vaccine — one, a vaccine based on the whole virus (this could be either inactivated, or an attenuated [weakened] virus vaccine); two, a non-replicating viral vector vaccine that uses a benign virus as vector that carries the antigen of SARS-CoV; three, nucleic-acid vaccines that have genetic material like DNA and RNA of antigens like spike protein given to a person, helping human cells decode genetic material and produce the vaccine; and four, protein subunit vaccine wherein the recombinant proteins of SARS-COV-2 along with an adjuvant (booster) is given as a vaccine.
Vaccine development is a long, complex process. Unlike drugs that are given to people with a diseased, vaccines are given to healthy people and also vulnerable sections such as children, pregnant women and the elderly. So rigorous tests are compulsory. History says that the fastest time it took to develop a vaccine is five years, but it usually takes double or sometimes triple that time.
Van Kerkhove said: “What I was referring to yesterday were very few studies, some two or three studies that have been published, that actually try to follow asymptomatic cases.”
“That's a very small subset of studies,” she continued. “I used the phrase 'very rare,' and I think that that is (a) misunderstanding to state that asymptomatic transmission globally is very rare. What I was referring to was a subset of studies.”
Studies show people with the novel coronavirus, which causes COVID-19, are most infectious when they first show symptoms, Kerkhove said.
She added that a sub-set of people do not develop symptoms, but can still infect others, and as many as 40 percent of transmissions may be by asymptomatic cases.
(With inputs from the Associated Press)Click here for Moneycontrol’s full coverage of the novel coronavirus pandemic