The decision comes after the first reports of patients whose infection could not be linked to international travel emerged on Monday. The majority of Sweden's patients have contracted the virus in northern Italy or via direct contact with people who contracted it in northern Italy. Other countries include Iran, US and Germany.
The Public Health Agency said there were signs of so-called community infection in the Stockholm healthcare region and Västra Götaland in western Sweden, but no widespread such outbreak in Sweden as a whole.
“We're talking about a handful of people that we can classify as domestic cases. Perhaps fewer than ten,” Public Health Agency director-general Johan Carlson told a press conference on Tuesday.
Health officials stressed that it could not confirm that the virus was spreading in Sweden, but said that because there were a few cases where they could not link it to anything else, it could not be ruled out.
They also said the increased risk should not be interpreted as a forecast of a widespread outbreak, but urged people to stay at home if they experience symptoms of the coronavirus, however mild.
“Everyone with symptoms of respiratory infection, even mild, are urged to avoid social contacts which risk spreading the infection,” said the Public Health Agency in a statement on its website on Tuesday.
“It is especially important that those who work in elderly care do not go to work if they develop symptoms of a respiratory infection. Relatives should also avoid unnecessary visits to hospital and care homes, and never visit if you have respiratory symptoms. Avoiding unnecessary visits protect the most vulnerable,” it said.
Sweden has confirmed more than 320 coronavirus cases so far, with more than 60 new cases reported on Tuesday. The majority have mild symptoms, but two patients in Stockholm are currently in intensive care.
No one in Sweden has died from the virus. Most of Sweden's patients are aged 40-60, said health officials, but noted that this may be because more people in that age group had been travelling in northern Italy.
Around 80 percent of those infected with the virus suffer only mild symptoms according to the World Health Organisation, although even patients with mild symptoms can spread the disease. Groups such as the elderly and those with pre-existing health conditions are thought to be particularly at risk (read more about precautionary measures here).
The coronavirus is a respiratory illness and initially similar to a common cold. The outbreak in the Chinese city of Wuhan – which is an international transport hub – began at a fish market in late December and since then more than 4,000 people have died, with more than 116,000 confirmed cases globally.
More than 64,000 people have recovered from the infection, according to John Hopkins CSSE.