Carriers without symptoms still have coronavirus in high amounts: study

People carrying the coronavirus keep high levels of the virus in their nose, throat, and lungs whether they show symptoms or not, a study published Thursday showed.

The study published in the JAMA Internal Medicine gave evidence that the viral load—the amount of virus in an infected person’s blood—is similar between asymptomatic and symptomatic carriers.

The research team, led by Seungjae Lee from Soonchunhyang University College of Medicine, said their findings “offer biological plausibility” to an asymptomatic person transmitting the virus.

The study tested 303 people aging from 22 to 36 infected with COVID-19 in Cheonan, South Korea. Of the total, 193 showed symptoms of infection, and 110 were asymptomatic.

Of the asymptomatic cases, 89 never presented any symptoms at all in the span of 20 days since March 6. This finding sheds light on the confusion between those who are asymptomatic, and those who are “presymptomatic”—meaning they will fall ill eventually.

The researchers regularly collected respiratory samples after the eighth day of isolation. The samples revealed the amount of viral genetic material from asymptomatic patients is similar to those in patients with symptoms.

The median time for patients to test negative for coronavirus is at 17 days for asymptomatic patients, two and a half days shorter than those of symptomatic patients.

The researchers suggested it may be necessary to isolate asymptomatic patients. But they also clarified that the detection of viral genetic material does not equate to the virus being transmissible.