People who are infected with SARS-CoV-2 may retain enough active virus beyond a 10-day quarantine period to potentially pass the infection to others, a small new study has found.
Using a new test that can detect viral activity in PCR swab samples, investigators found that 13% of 176 study participants continued to show clinically relevant levels of the virus after 10 days. Some retained these levels for up to 68 days, they reported. An active virus could pose a potential risk of continuing transmission, the researchers said.
“Our results suggest that potentially active virus can sometimes persist … and could pose a potential risk of onward transmission,” wrote lead author Merlin Davies, a Ph.D. student at the University of Exeter Medical School.
If confirmed, the results are particularly concerning for residents of nursing facilities and other settings with vulnerable populations, he added.
“In situations such as hospital inpatient care or patients returning to long-term care facilities following hospital discharge … it may be prudent to obtain molecular evidence of remission to protect vulnerable populations,” he and his colleagues wrote.
“We may need to ensure people in those settings have a negative active virus test to ensure people are no longer infectious,” Davies said in a statement.
Standard polymerase reaction tests show whether the test taker has had the virus, but cannot tell whether a virus is still active or a patient continues to be infectious, the researchers noted. The test used in the current study gives positive results only when the virus is active and potentially infectious, they said. They foresee larger studies to confirm their results, which could theoretically support the use of the new test in high-risk settings to stop the spread of COVID-19.
The study was published in the International Journal of Infectious Diseases.
