One in 10 people may have clinically relevant levels of potentially infectious SARS-CoV-2 past the ten-day COVID isolation period, according to new research.
The research follows the recent announcement by the UK Government that the covid isolation period after infection will be reduced to five days in England.
The study, published in the International Journal of Infectious Diseases, found that 13% of people still exhibited clinically relevant levels of the virus after ten days, meaning they could potentially still be infectious after covid isolation. 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.
An adapted test detecting active covid
Professor Lorna Harries, of the University of Exeter Medical School, oversaw the study. She said: “While this is a relatively small study, our results suggest that potentially active virus may sometimes persist beyond a ten-day covid isolation period, and could pose a potential risk of onward transmission. Furthermore, there was nothing clinically remarkable about these people, which means we wouldn’t be able to predict who they are”.
The study, led by the University of Exeter and funded by Animal Free Research UK, 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.
Conventional PCR tests work by testing for the presence of viral fragments. Whilst, 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.
Lead author Merlin Davies, of the University of Exeter Medical School, said: “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. We may need to ensure people in those setting have a negative active virus test to ensure people are no longer infectious. We now want to conduct larger trials to investigate this further.”
Animal Free Research UK CEO, Carla Owen, said: “The University of Exeter team’s discovery is exciting and potentially very important. Once more, it shows how focusing exclusively on human biology during medical research can produce results that are more reliable and more likely to benefit humans and animals.
“Pioneering animal-free work is providing the best chance of not only defeating COVID-19 but also finding better treatments for all human diseases.
“The results also send a loud and clear message to the Government to better fund modern medical research and make the UK a world leader in cutting edge, kinder science.”
COVID isolation cut down to only five days in England
The UK Government announced in England, people with SARS-CoV-2 can end their covid isolation after five full days, as long as they test negative on day five and day six. Those who are able to end their covid isolation period on or after day six are strongly advised to wear face coverings and limit close contact with other people in crowded and poorly ventilated. They are also encouraged to work from home if possible and minimise contact with anyone who is at higher risk of severe illness if infected with COVID-19. However, you must stay in covid isolation until you have had two consecutive negative tests taken on separate days.
This will be effective from Monday 17 January 2022.