The self-isolation period varies from 14 days according to the WHO to 5 days according to the current duration in the US and 10 days in the UK.
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.”
Read the full-tex of this article at BMJ -2021-Dec 30