Some Covid-19 patients can be infectious even after ten days, study finds

One in ten people could still be infectious for SARS-CoV-2, the virus that causes Covid-19, after the 10-day quarantine period, a study has found.

The research, published recently in the International Journal of Infectious Diseases, used a newly adapted test that can detect whether the virus was potentially still active.

The test was applied to samples from 176 people in Exeter, UK, who had tested positive in standard PCR tests.

The team led by researchers from the University of Exeter found that 13% of people still had clinically relevant levels of the virus after 10 days, meaning they could still be infectious.

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Some people retained these levels for up to 68 days, the researchers found.

They believe this new test should be applied in settings where people are vulnerable, to stop the spread of Covid-19.

“Although a relatively small study, our results suggest that potentially active virus can sometimes persist beyond a 10-day period and could pose a potential risk for further transmission,” said Professor Lorna Harries, from the University of Exeter Medical School, who supervised the study.

“Furthermore, there was nothing clinically remarkable about these people, which means we wouldn’t be able to predict who they are,” Harries said.

Conventional PCR tests work by testing for the presence of viral fragments.

Although these tests can tell if someone has recently had the virus, they cannot detect if it is still active and if the person is contagious.

However, the test used in the latest study only gives a positive result when the virus is active and potentially capable of transmission.

“In some settings, such as people returning to care homes after illness, people who continue to be infectious after ten days could pose a serious public health risk,” said the study’s lead author. , Merlin Davies, of the University of Exeter Medical School.

“We may need to make sure people in these environments have a negative active virus test to make sure people are no longer infectious,” Davies added.

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