Faces we see, coronavirus we do not know, says expert 3:32
(CNN) –– Covid-19 patients who do not have symptoms may have amounts of the virus in their bodies similar to those who are symptomatic, according to a new study from South Korea. This would suggest that they could transmit the virus to other people.
The research, published in the journal JAMA Internal Medicine on Thursday, included data from 303 COVID-19 patients who were in isolation in March inside a community treatment center in South Korea. The participants, mostly young adults, had a mean age of 25 years.
Of these patients, 193, or 63.7%, had symptoms at the time of isolation, according to the study. While 110 patients appeared to have no symptoms.
Only 19.1% of asymptomatic patients eventually developed symptoms during isolation, compared to 80.9% who remained asymptomatic and had no symptoms for an average of 24 days who were monitored in the study.
Nasal and throat swab samples were taken from each patient. The researchers then analyzed those tests and examined the viral genetic material called RNA, taking a closer look at viral loads, which refers to the amount of virus a person has in their body.
The danger of silent covid-19 transmitters 1:09The study found that the viral load in asymptomatic patients appeared to be similar to that of those with symptoms.
The researchers highlighted in their report that the viral loads of asymptomatic patients from when they were diagnosed until they were discharged from the treatment center tended to decrease more slowly than those of those who were symptomatic and presymptomatic.
The study had some limitations, including that more research is needed to determine whether similar findings would result in a larger group of patients. The report also failed to determine how infectious each person was.
"Although the high viral load we observe in asymptomatic patients raises a clear possibility of risk of transmission, our study was not designed to determine this," the investigators wrote.
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"It is important to note that detection of viral RNA is not equivalent to an infectious virus being present and transmittable," they added. "For a better understanding of viral shedding and potential transmission of asymptomatic infection, large rigorous epidemiological and experimental studies are needed," they completed.
Different research has previously suggested that "silent transmission" - that is, the spread of the virus by someone without obvious symptoms - could be responsible for half of all coronavirus cases in the United States.
Transmission through people without symptoms, or during the few days before they appear, may be the main reason for the spread of COVID-19, according to an earlier study published in July in the Proceedings of the National Academy of Sciences .
On Monday, America's leading infectious disease expert, Dr. Anthony Fauci, said that asymptomatic transmission is a determining factor in community spread.
Is the risk of contagion from asymptomatic patients less? 2:28“There are people who are spreading it [the coronavirus] and who do not have any symptoms, and we know that it definitely happens. It is difficult to identify it, and it is difficult to do detection, isolation and contact tracing, "said Fauci, director of the National Institute of Allergies and Infectious Diseases, during a press conference with Connecticut Governor Ned Lamont.
"It is not easy to identify who these propagators are," said Fauci. "That makes it much more difficult to contain."
CNN's Sandee LaMotte, Lauren Mascarenhas and Andrea Kane contributed to this report.
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