Asymptomatic patients may be key to end the coronavirus pandemic: Report

With the coronavirus
pandemic having claimed more than 700,000 lives in the course of seven months, researchers are wondering if the key to stopping it may
lie in the high percentage of asymptomatic patients in the world.

According
to the Washington Post, Monica Gandhi, an infectious-disease specialist at the
University of California at San Francisco, was startled by the vast number of
individuals who were virtually unscathed by the coronavirus and decided to delve
deeper into the mystery.

Could the ‘dose’
of exposure to the virus be the reason behind the lack of symptoms? Genetics
could be another differentiator or maybe some people have a partial resistance
against the virus.

Efforts to answer
these questions are finally starting to pay dividends, with some hoping the knowledge
gained from the research may help develop vaccines and other therapies, or even
help pave new avenues towards herd immunity.

“A high
rate of asymptomatic infection is a good thing. It’s a good thing for the
individual and a good thing for society,” the Washington Post quoted Gandhi as
saying.

There are
many uncertainties regarding the coronavirus. Irregular transmission in different
parts of the world has much milder impact on children. But the most baffling
aspect is the extraordinarily high numbers of those exhibiting mild or no
symptoms at all. The Centers for Disease Control and Prevention has estimated
that almost 40 percent of total infected individuals are asymptomatic.  

The
numerous mysteries have sent scientists in different directions, with some attempting
to understand the role that age and genetics might play by studying receptor
cells, which is used by the virus to enter the body. Others are studying if
wearing masks filters out enough of the virus that patients exhibit only mild or
no symptoms.

One theory
has emerged that has generated much excitement in the scientific community in
recent weeks, according to which some people already possess partial immunity
from the virus.

SARS-CoV-2,
the technical name of the virus that causes the disease COVID-19, was first discovered
on December 31, 2019. It was assumed that humans would have no immunity from it
whatsoever as it had never been seen in our species before. The partial
immunity theory suggests that assumption may have been wrong.

Studies
have suggested that a portion of the population may be partially protected from
the coronavirus due to ‘memory’ T cells, a component of the immune system that recognizes
specific invaders. This aspect of the immune system could develop either from childhood
vaccinations or from encounters with other coronaviruses like the one that causes
the common cold.

“This might
potentially explain why some people seem to fend off the virus and may be less
susceptible to becoming severely ill,” Francis Collins, Director of the US’ National Institutes of Health, said in a recent blog post.

Some researchers
also suggest that studies have underestimated the percentage of people with partial
immunity from the coronavirus. In major cities like Barcelona, Boston and
Wuhan, the number of people estimated to have antibodies and thus presumed to
be immune is in the single digits. However, the community’s immunity rate would
rise higher if others had partial protection from T-cells.

Hans-Gustaf
Ljunggren, a researcher at Sweden’s Karolinska Institute, said that would be “very
good news from a public health perspective.”

Some
experts are speculating whether preexisting immunity may be the reason behind trends
like the declining infection rate in Sweden, where a widespread lockdown or
requirement to wear a mask was not enforced.

Others, however,
are much more apprehensive about such conclusions. The United States’ foremost
authority on infectious diseases, Anthony Fauci acknowledged the ongoing
studies pertaining to these ideas, although such theories are premature. He said
some level of immunity in certain individuals may be a possibility.

He further
stated that the amount of virus an individual is exposed to, which is known as the
inoculum, “is almost certainly an important and likely factor,” based on
existing data on other viruses.

However, Fauci
said that there are a multitude of other factors like youth and general health,
that decides an individual’s fate once they contract the virus.

“There are
so many other unknown factors that maybe determine why someone gets an
asymptomatic infection. It’s a very difficult problem to pinpoint one thing,” Fauci said.

However, there is
strong evidence to suggest a correlation between wearing masks and
asymptomatic patients.

In an article published in the Journal of General
Internal Medicine, Gandhi highlighted that in the early phases of the outbreak,
where people were not wearing masks, 15% of total cases were asymptomatic.
That number shot up to 40-45% in some of the later stages, when the
practice of wearing masks became more mainstream.

Contrary to
conventional arguments that asymptomatic patients might inadvertently spread
the virus to others, Gandhi is of the opinion that having more asymptomatic
patients may be a good thing.

“It is an
intriguing hypothesis that asymptomatic infection triggering immunity may lead
us to get more population-level immunity. That
itself will limit spread,” she said.