SARS-CoV-2 Can Persist For Weeks In Asymptomatic Individuals

Asymptomatic individuals who test positive for SARS-CoV-2, the virus that causes COVID-19, can carry the virus for several weeks while remaining symptom-free, researchers from China report.

Several reports have documented the existence of truly asymptomatic individuals infected with SARS-CoV-2, and emerging evidence suggests that these individuals can be contagious.

Dr. Yanfeng Pan of the First Affiliated Hospital of Zhengzhou University and colleagues evaluated the clinical characteristics and asymptomatic carrier transmission of 26 persistently asymptomatic patients who tested positive for SARS-CoV-2 RNA.

Six patients reported having traveled to Wuhan without a clear contact with a source of infection, 18 had identifiable contacts with confirmed or possible patients, and two had an unknown contact history.

Among the patients' close contacts, only two were infected with SARS-CoV-2.

In the 18 patients with a clear source of infection, the median time from contact to testing positive was 19 days, compared with 15 days in the six patients who recently traveled to Wuhan.

All 26 patients had normal lymphocyte counts, but 10 patients had typical and seven atypical pulmonary manifestations on the CT scan. Chest CT improved over time in the patients with typical pulmonary manifestations.

The time from diagnosis to being confirmed SARS-CoV-2-free was 10 days or less in 15 patients, 20 days or less in 23 patients, and more than 20 days in three patients, the authors report in the Journal of Infectious Diseases.

The median time from contact to the last positive SARS-CoV-2 RNA test was 21.5 days (range, 10 to 36 days), and the interval was longer than 30 days in four patients. Two patients had positive SARS-CoV-2 RNA tests following negative results.

All 26 patients were discharged from the hospital after admissions ranging from 10 to 24 days (median, 13 days).

"SARS-CoV-2 can be present for a long time in some asymptomatic patients; the change in nucleic acid test results from positive to negative in some patients may not occur synchronously with the CT improvement; and false negatives of the nucleic acid test for SARS-CoV-2 may occur," the authors conclude.

Dr. Pan did not respond to a request for comments.

—Reuters Staff

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