A new study is suggesting that 10 days of quarantine may not be enough, with as many as one in 10 people still contagious after that point.
According to a small UK study, which was published in December in the International Journal of Infectious Diseases and looked at 176 patients who had previously tested positive for COVID-19 with PCR, a new type of test found It was found that some patients were infectious. Exceeding the standard 10-day quarantine period.
“Although this is a relatively small study, our results suggest that potentially active virus can sometimes persist after a 10-day period, posing a potential risk of further transmission,” said University of Exeter. Medical school professor Lorna Harris said. inspected the study, said in a press release. “Furthermore, there was nothing clinically remarkable about these people, which means we would not be able to predict who they are.”
PCR tests are the gold standard for identifying whether a person has COVID-19, and work by looking for viral fragments. But they don’t tell us whether a person is currently infectious, according to the study, because those fragments may still be present in the system after viral clearance.
Another way to test is to look for subgenomic RNAs, which are produced when a virus is actively replicating itself, the researchers said.
The researchers looked at RNA from samples collected from 176 individuals who had previously tested positive for COVID-19 by PCR between March 17, 2020 and November 29, 2020. Of these patients, 74 were asymptomatic, 36 had mild disease, 22 had moderate. disease and 33 were classified as severe disease.
They found that 13 percent of the sgRNA-positive cases displayed clinically relevant levels of virus even after 10 days.
For the 17 people in the study, subsequent samples were available. Five of these individuals showed sgRNA positive by day 68.
The researchers hope that this type of testing could be applied in high-risk scenarios, such as testing health care workers or those working in long-term care.
“In some settings, such as people returning home after illness, being contagious even after ten days can pose a serious public health risk,” study lead author Marilyn Davis said in the release. “We may need to make sure that people in those settings have a negative active virus test to ensure that people are no longer contagious. We now want to do larger tests to investigate this further.”
Some previous studies have suggested that the presence of sgRNA does not necessarily mean that the virus is definitely active, and the researchers acknowledge that further research is needed on this issue.
But this shows that the 10-day rule may not be absolute for every case.
“Given the apparent potential for onward transmission in these cases, more targeted studies to detect and investigate secondary cases with more than 10 days of transmission should now be performed in these populations,” the study said in its conclusion.