As Sweden and Denmark introduce tougher measures to tackle a surge in coronavirus, the top Swedish epidemiologist has warned that some people in his country are resistant to changing advice.
Prof Anders Tegnell said many people are not wearing masks on public transport because of his agency's previous scepticism towards face coverings.
Face masks are now required on Sweden's public transport when crowding cannot be avoided.
Prof Tegnell said masks are an effective way to stop transmission, particularly in crowded spaces, and that health officials should work to change attitudes to promote their use.
“We can’t get away from the fact that we have been sceptical towards face masks, and people have understandably picked up on that, and have it in the back of their mind. And then it’s hard to change that attitude,” he told newspaper Dagens Nyheter.
In neighbouring Denmark, new restrictions were announced on Friday closing entertainment venues, including amusement parks and museums, in response to a rise in Covid-19 cases that experts said was faster than expected.
“Theatres, cinemas and concert halls, they will have to close,” Prime Minister Mette Frederiksen said. “We need to limit our activity. We all need to limit our social contacts.”
The restrictions, which come into force on Sunday for four weeks, were announced alongside a record of more than 11,000 cases in the previous 24 hours.
Prof Tegnell, who is known for his hands-off approach to the Covid-19 pandemic, said that face masks are useful in situations where crowding cannot be avoided.
Sweden implemented one of Europe's most lenient coronavirus measures last year, with face masks and other mandatory social distancing dismissed as unnecessary under Prof Tegnell's strategy.
But by the end of 2020, the country was forced to implement strict new restrictions – such shop closures and curbs on gatherings – to tackle a surging infection rate that topped 5,000 new cases per day.
Sweden has opted against lockdowns throughout the pandemic and relied on mostly voluntary measures aimed at social distancing.
It has seen several times more deaths per capita than its Nordic neighbours but fewer than most European countries that opted for strict lockdowns.
In October, a commission investigating the country's pandemic response criticised authorities' slow and inadequate response, championed by advisers such as Prof Tegnell.
Sweden reported 4,022 new cases on Thursday – lower than the day before but among the highest daily increases since late spring.
Authorities also warned tighter restrictions may well be announced next week when the Public Health Agency publishes an update on how it sees the pandemic developing ahead.
Sweden, which has a population of 10 million, now has more than 500 patients requiring care for Covid-19, including 79 in intensive care.