Shortened isolation – One in three could still infect others after five days of isolation

On Wednesday, the Federal Council announced that the isolation and quarantine period would be reduced to five days. The change went into effect on Thursday. With the adjustment, the Federal Council wants to help the economy: the many absences are causing problems for many companies. People who do not show any symptoms for 48 hours should now come out of isolation – without a negative test result.

This decision has drawn some criticism. For example, the President of the Greens and National Councilor Balthasar Glättli writes on Twitter: “A high-risk strategy that accepts many victims on the way to the endemic phase.”

The shortened isolation also worries Huldrych Günthard, senior physician at the clinic for infectious diseases and hospital hygiene at the University Hospital Zurich: “There is a certain risk that positive people will still be highly contagious and go back to work after five days of isolation.”

According to an English study that has not yet been published, an infected person would still be around 30 percent contagious after five days – after seven days around 15 percent and after 15 days around five percent. “That is a significant difference and, in combination with our high number of cases, could lead to significantly more infections,” says the infectiologist. Epidemiologist Marcel Salathé also referred to the English study on Twitter.

According to Günthard, in a perfect world one would have to test oneself – but the capacities for this are hardly available at the moment. Günthard would have expected at least a recommendation for wearing an FFP2 mask up to ten days after the positive result: “I am very surprised that the Federal Council did not make this recommendation.”

The Ticino infectiologist Andreas Cerny says: “I am not aware of any data that would show that you could no longer infect anyone after five days of isolation.” A study from Japan (see below), for example, shows that the people examined who had been infected with omicron seven to nine days after the infection still had a similarly high viral load as shortly after the infection.

For Cerny, the Federal Council’s decision is “not scientifically supported and is not in line with the guidelines of our neighboring countries”. Quarantine and isolation are measures intended to break chains of infection. “The early release of infected people from the quarantine can lead to new chains of infection and is therefore not suitable for slowing down the spread, quite the opposite,” says Cerny. There is a risk that infected people will come out of isolation too early and cause new chains of infection.

GLP National Councilor Martin Bäumle still considers the federal government’s approach to be risky. He advocates wearing an FFP2 mask for a few days after isolation: “I would have expected that to be an urgent recommendation from the Federal Council.” It is known that Omikron can still be transmitted to vaccinated and boosted people.

The director of the Swiss Tropical and Public Health Institute, Jürg Utzinger, is more relaxed about the situation: “The decision to shorten isolation is certainly not a zero-risk strategy,” he says. Nevertheless, he considers it reasonable and sensible for three reasons: “Firstly, a large part of the population is vaccinated and new data suggest that vaccinated people are infectious for a shorter period of time.”

Secondly, according to Utzinger, we know “that the incubation period, i.e. the time between infection and the appearance of the first symptoms, is only around three days for omicrons, shorter than for delta or the wild types.” When the incidence is very high, as is currently the case in Switzerland, the relationship between the benefits and costs of isolation and quarantine also decreases. “In the current situation with high numbers of infections, in which omicron is dominant and a large part of the population is vaccinated, it makes perfect sense that the duration of the isolation has been shortened.” In addition, the decision is also important from a societal point of view: “It is central to both the economy and the maintenance of basic services that not too many people are in long-term isolation at the same time.”