Intended for healthcare professionals


Covid-19: Is it safe to reduce the self-isolation period?

BMJ 2021; 375 doi: (Published 30 December 2021) Cite this as: BMJ 2021;375:n3164

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  1. Elisabeth Mahase
  1. The BMJ

Two years after the covid-19 outbreak began and a year since vaccinations started, many governments are now reducing the length of time people with covid have to isolate. Elisabeth Mahase looks at the evidence behind the different strategies

What are the isolation rules in different countries?

In the US, new rules mean that people have to isolate for only five days, while in the UK they have to isolate for 10 days unless they have negative lateral flow tests on days 6 and 7, at which point they can stop isolating.12

In France and Japan the isolation period is 10 days, while in New Zealand it is 10 days if the person is fully vaccinated (including 72 hours free of symptoms) but 14 days if they are unvaccinated (again including 72 hours free of symptoms). Germany, Jordan, and Brazil are following the World Health Organization’s recommended 14 day isolation period.

Could the UK follow the US’s five day rule?

The UK prime minister, Boris Johnson, is reportedly resisting calls for the isolation period to be cut to five days, at least until more evidence is available about the effects of the recent move from 10 to seven days.3

Regarding a potential move to five days, NHS Providers’ chief executive, Chris Hopson, said, “Trust leaders are currently grappling with the need to keep vulnerable patients safe from catching covid-19 in a healthcare setting and ensuring staff who are having to isolate due to covid-19 can safely return to work as quickly as possible. The key concept here is safe return . . .We must follow the science and evidence on what is safe and what is not.”

Is it safe to reduce the self-isolation period from 14 days?

While most countries started out with WHO’s recommended 14 day isolation period, many have reduced this requirement during the pandemic. Michael Ryan, executive director of the WHO Health Emergencies Programme, called the changes “judgment calls” made to deal with covid-19 cases while minimising the impact on people’s social, economic, and educational lives.

Speaking at a press conference on 29 December, he said that most people would incubate and show symptoms or be positive within the first six days of becoming infected. The chances of transmitting the disease after that are lower, although still a risk.

“There are trade-offs,” said Ryan. “If people shorten the quarantine period, there will be a small number of cases that will develop disease and potentially go on to transmit because they’ve been let out of quarantine earlier. But that will be a relatively small number, and a lot of people who won’t transmit will also be released from that quarantine.

“So, it is a trade-off between the science and being absolutely perfect in what you try to do, but then having the minimal disruption that you can possibly have to your economy and your society. And governments are struggling to find that balance.”

Has omicron changed anything?

The US Centers for Disease Control and Prevention certainly thinks so. In its five day isolation announcement it said that the change from 10 days was motivated by evidence that most omicron transmission occurred one to two days before the onset of symptoms and in the two to three days thereafter.4

However, Ryan warned against countries changing rules on the basis of early data. He said, “The data is not certain because we’re dealing with a very limited number of studies and a limited number of individuals. We’re also talking mainly about younger people. Maybe younger people have a shorter duration than older, but we just don’t know. So, we need to be very careful with interpreting these data.

“But I think the most important thing at this moment is that we need to be careful about changing tactics and strategies immediately on the basis of what we’re seeing in early data.”

Should lateral flow tests be used to reduce isolation?

Commenting on the UK’s policy to allow people out of isolation early if they have two negative lateral flow test results, Ryan said that it was again a “judgment call.” He said, “The window within which [the antigen test] can pick up the virus is narrower than the window with the PCR test, which is much more sensitive. But again, the antigen test is very convenient. It’s very quick and can be done at home, it can be done on site, and there are a lot of practical real world advantages to doing that. So again, it’s a trade-off.”

Are people still following the isolation rules?

In the UK, the Office for National Statistics looked at the behaviour of 895 individuals required to self-isolate after testing positive for covid-19 between 29 November and 4 December 2021.5 This showed that around three quarters (74%) fully adhered to the requirements throughout their self-isolation period—a similar level to that reported in July (79%), September (78%), and November 2021 (75%).

However, one in four people (25%) reported having carried out at least one activity during self-isolation that was not adherent to the requirements, such as leaving their home or having visitors for reasons not permitted under legislation.

Tim Gibbs, head of public services analysis at the Office for National Statistics, said, “We are continuing to see that a majority of those testing positive for covid-19 are following self-isolation requirements. Although there are negative impacts of self-isolation, such as on wellbeing and mental health, it’s critical that we continue to follow self-isolation rules.”

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