Finally, researchers from South Korea seem to have come up with some convincing evidence to one of the most controversial questions pertaining to the spread of SARS-CoV-2: whether an asymptomatic patient can transmit the virus to another individual.
WHO, which has been spearheading the global response to the pandemic, has been fending off researchers who point out avid asymptomatic spread of the virus as one of the most deceptive characteristics of the novel coronavirus, citing “lack of scientific evidence”.
Infected people looking apparently healthy and showing no outward symptoms will be carrying as much virus in their nose, throat and lungs as patients who are sick with symptoms, shows a study by South Korean researchers published in the latest issue of JAMA Internal Medicine.
Conducted in a cohort of 303 patients with SARS-CoV-2 infection isolated in a community treatment centre in the Republic of Korea, the study was an attempt to assess whether there were viral load differences between asymptomatic and symptomatic patients with severe infection.
Of these, 110 (36.3%) were asymptomatic at the time of isolation and 193 were symptomatic. In the group of patients without any symptoms, 21 people (19.1%) developed symptoms during isolation while 89 remained symptomless throughout.
On analysing the samples taken from the patients, the researchers found that the cycle threshold values of RT PCR for SARS-CoV-2 in asymptomatic patients were similar to those in symptomatic patients.
Many individuals with SARS-CoV-2 infection remain asymptomatic for a prolonged period, and the viral load is similar to that in symptomatic patients. Therefore, isolation of infected persons should be performed regardless of symptoms, the researchers conclude.
In most places, infected people showing no visible symptoms are kept in isolation usually for a shorter duration as many experts believe that asymptomatic people shed less virus because they seldom cough or sneeze unlike those who are clearly sick with the disease.
On the other hand, unlike sick patients who tend to stay in bed, the symptomless infected unwittingly infect many others as they continue socialising.
Recently, Dr Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, also alerted that about 40 percent of the population have no symptoms and they are inadvertently propagating the virus by infecting others with serious consequences.
“[Even though you have no symptoms] you’re going to infect someone else who will then infect someone else. Then, someone who’s vulnerable to severe consequences will get infected. That could be somebody’s father, mother, or grandmother,” Dr Fauci said.
Asymptomatic people, particularly the young, may fan out into the society and keep the virus circulating at high levels, experts say.
The study suggests that transmission of the virus by the symptomless spreaders could be the cause of a large number of infections which could not be traced to an index patient or a definitive source.
Perhaps, the ability of the virus to spread stealthily is one of the most deceptive traits of SARS-CoV-2 that makes it difficult to contain. Several other viruses can be spread by people without symptoms, but usually at negligible levels.