One in ten people may still be infectious for COVID after ten days

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In a new study from the University of Exeter, researchers found one in 10 people may have clinically relevant levels of potentially infectious SARS-CoV-2 past the 10 day quarantine period.

They used a newly adapted test that can detect whether the virus was potentially still active. It was applied to samples from 176 people in Exeter who had tested positive on standard PCR tests.

The team found that 13% of people still exhibited clinically-relevant levels of virus after 10 days, meaning they could potentially still be infectious.

Some people retained these levels for up to 68 days. The authors believe this new test should be applied in settings where people are vulnerable, to stop the spread of COVID-19.

The results suggest that a potentially active virus may sometimes persist beyond a 10 day period, and could pose a potential risk of onward transmission.

Conventional PCR tests work by testing for the presence of viral fragments. While they can tell if someone has recently had the virus, they cannot detect whether it is still active, and the person is infectious.

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

The team says in some settings, such as people returning to care homes after illness, People continuing to be infectious after ten days could pose a serious public health risk.

The government may need to ensure people in those setting have a negative active virus test to ensure people are no longer infectious.

The research is a collaboration between the University of Exeter Medical School, the Royal Devon & Exeter NHS Foundation Trust, and the NIHR Exeter Clinical Research Facility.

If you care about COVID, please read studies about the most effective face-mask practices to reduce spread of COVID-19, and the treatment options for COVID-19.

For more information about health, please see recent studies about drug that could help treat lung damage in COVID-19, and results showing that new findings may help treat blood clots in COVID-19.

The study is published in International Journal of Infectious Diseases. One author of the study is Professor Lorna Harries.

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