Coronavirus: Asymptomatic patients excrete as much virus

COVID-19 patients with and without symptoms are equally contagious: asymptomatic people have as much virus in the nose, mouth and lungs as patients who cough and have a fever

  • The researchers examined 303 patients who were isolated in a treatment center in Cheonan, South Korea
  • The viral load in patients with asymptomatic coronavirus was very similar to that in patients with symptoms
  • The amount of virus in the noses and throats of symptomatic patients tended to decrease somewhat more slowly over time than in asymptomatic patients
  • Health experts say testing and contact tracking need to be stepped up so that those without symptoms can be isolated just as quickly

There is further evidence of the dangers of asymptomatic patients with the novel coronavirus.

The researchers found that the viral load of people without symptoms is just as high as that of infected people who cough and have a fever.

Since asymptomatic patients also contained as much of the nose and throat virus known as SARS-CoV-2, they were also likely to spread the disease.

The Seoul Hospital team at Soonchunhyang University in South Korea says the results further indicate the importance of speeding up testing and contact tracking so that people without symptoms can quickly isolate and reduce the risk of transmission.

A new study found that the viral load of patients with asymptomatic coronavirus was very similar to that of patients with symptoms (above).

For the study published in JAMA Internal Medicine, the team examined 303 patients infected with the virus between March 6 and March 26.

All participants were isolated in a community treatment center in Cheonan, South Korea, a city south of the capital city of Seoul.

Of these, 63.7 percent were symptomatic when isolated. Of the 36.3 percent of asymptomatic patients, 21 developed symptoms during isolation.

The most common signs of infection are fever, cough and shortness of breath, but also repeated shaking with chills and new taste or smell loss.

The researchers then examined the cycle thresholds (Ct), which relate to the detection of the virus and the viral load of a person, during the test.

The Ct values ​​in asymptomatic patients were very similar to those in patients with symptoms.

The team also examined negative conversion tests, in which samples were taken from the upper and lower airways and defined as negative when both came back negative.

The results showed that the viral load in symptomatic patients tended to decrease somewhat more slowly over time than in asymptomatic patients.

On day 14 of isolation, 33.7 percent of patients without symptoms received a negative coronavirus test compared to 29.6 percent of symptomatic patients.

Until the 21st day 75.2 percent of asymptomatic patients received negative test results compared to 69.9 percent of patients with symptoms.

The median from diagnosis to first negative conversion was 17 days in asymptomatic patients and 19.5 days in symptomatic patients.

In addition, the team found no significant differences in the amount of viral RNA between those with and without symptoms.

"Many people with SARS-CoV-2 infection remained asymptomatic for an extended period of time and the viral load was similar to that of symptomatic patients," the authors wrote.

Therefore, isolation of infected people should be done regardless of symptoms.

"Because transmission by asymptomatic patients with SARS-CoV-2 can be a key factor for dissemination in the community, population-based monitoring and isolation of asymptomatic patients may be required."


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