Scientific advice to Welsh Government suggests that ending Omicron isolation after five days may be too soon

Scientific advisors to the Welsh Government have pointed to evidence that ending Omicron isolation after five days may be too soon.

Since 25 January people who test positive for Covid-19 are able to leave self-isolation after five full days if they have two negative lateral flow tests.

Health Minister Eluned Morgan confirmed the change after England moved from seven to five days of self-isolation.

However, the latest technical advisory briefing of Covid-19 advice presented to the Welsh Government points to evidence that five days may be too soon to end isolation.

The advice given to the Welsh Government on Thursday of last week, but published today, points to a pre-print study of the use of lateral flow devices among US healthcare workers looking to exit self-isolation to return to work.

The study “shows that a substantial proportion of individuals with COVID-19 are likely still contagious after day 5 of illness, regardless of symptom status”.

“Early liberation from isolation without a supporting negative LFT should be undertaken only with the understanding that inclusion of individuals on day 6-10 of illness in community or work settings may increase the risk of COVID-19 spread to others,” the briefing said.

The advice notes that this would run contrary to current Welsh Government guidance that “an individual should self-isolate for at least 5 days, after which they should exit self-isolation following 2 negative tests on 2 consecutive days”.

‘Isolation clock’

The research team involved examined 309 rapid antigen tests performed on 260 UChicago Medicine healthcare workers between January 2 and January 12, 2022. Those employees all tested between days five and 10 following the start of their COVID-19 symptoms (or the date of the first positive COVID-19 test, if they were asymptomatic).

The results, Researchers at the University of Chicago Medicine said, may indicate that a large number of people with COVID-19 are still likely contagious after the first five days of their illness, even if they feel fully recovered.

Having them return to work before 10 days of isolation without a negative rapid antigen test may increase the risk that they spread the virus to others, the researchers added.

The results showed 43% of rapid tests during the so-called “early-return period” were positive, even though individuals felt well enough to work.

The data was released February 2 and has not yet been peer-reviewed.

“The CDC isolation recommendations were based on studies collected mostly before the Omicron variant and before people had been vaccinated or infected. In those situations, symptoms generally didn’t start until a person had already reached their peak virus load,” said co-author Emily Landon, MD, Executive Medical Director, Infection Prevention and Control at UChicago Medicine, who was the paper’s first author.

“In those cases, ending isolation after five days might be reasonable, since earlier data showed few people still had live virus at that point. But with Omicron, we’re potentially seeing earlier symptoms — even before the peak virus load has been reached — which starts the isolation clock several days earlier and leaves more people contagious on days six to 10.”

‘Evidence’

Announcing the changes to the self-isolation period from seven to five days in January, Minister for Health and Social Services Eluned Morgan said that it was still one of the most effective ways of preventing the onward spread of this virus and disrupting its transmission.

“But self-isolating for long periods can have a negative impact on our mental health and can be damaging for our public services and the wider economy,” she said.

“After carefully reviewing all the available evidence, we believe that testing on days 5 and 6 together with 5 full days of isolation will have the same protective effect as a 10-day isolation period.

“But it is really important everyone self-isolates and uses lateral flow tests in the way advised to ensure they protect others from the risk of infection.

“The response from the public has been outstanding in Wales throughout the pandemic and we want to thank everyone for working with us to keep Wales safe.

“The booster jab has lessened the likelihood of severe cases of the virus and hospitalisation so I encourage anyone who is yet to have their vaccine to take up the offer.”