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On December 31 last year, Chinese media reported for the first time on an outbreak of viral pneumonia in Wuhan. In the last seven months, the deadly novel virus has infected over 20 million people worldwide, according to the date released by Johns Hopkins University.
Most coronavirus patients in India are asymptomatic, health minister Harsh Vardhan earlier said. "People in their 20s, 30s and 40s are increasingly driving the spread. Many are unaware they are infected," Takeshi Kasai, Western Pacific regional director, World Health Organisation on Tuesday said.
A high-rate of asymptomatic COVID-19 cases is a "good thing" for the society and could play a role in the ending of the pandemic, according to a researcher. The research by Monica Gandhi, an infectious-disease specialist at the University of California at San Francisco, is based on asymptomatic cases, according to The Washington Post.
"A high rate of asymptomatic infection is a good thing. It is a good thing for the individual and a good thing for society," Gandhi said.
According to the United States Centres for Disease Control and Prevention last month, 40% of people infected with the virus are asymptomatic.
When coronavirus first surfaced in December last year, health authorities labelled it a "novel" virus as it was the first time it was seen in humans who presumably had no immunity from the infection. However, this early and tentative evidence suggests that the assumption might have been incorrect.
One interesting hypothesis states that a part of the world's population may have partial protection due to "memory" T cells, a part of our immune system trained to recognise specific invaders. This may arise from cross-protection derived from standard childhood vaccinations, as per The Washington Post.
"This might potentially explain why some people seem to fend off the virus and may be less susceptible to becoming severely ill," National Institutes of Health Director Francis Collins was quoted as saying.
Hans-Gustaf Ljunggren, a researcher at Sweden's Karolinska Institute and others have suggested that public immunity to COVID-19 could be significantly higher as per the recommendations by serology studies.
But Anthony S Fauci, the US' top infectious-disease expert, stated in an interview that such theories are premature even as these ideas are being studied deeply. However, he acknowledged that partial pre-existing immunity in some individuals seems a possibility.
"There are so many other unknown factors that may determine why someone gets an asymptomatic infection. It is a very difficult problem to pinpoint one thing," Fauci said.
In an article published in the Journal of General Internal Medicine earlier this month, Gandhi said 15 people of the infected were asymptomatic in some early outbreaks of the pandemic, in which most people did not wear masks. But when people started to wear masks, the rate of asymptomatic patients was between 40 to 45%.
"It is an intriguing hypothesis that asymptomatic infection triggering immunity may lead us to get more population-level immunity. That itself will limit spread," Gandhi noted.
(With inputs from agencies)
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