Sweden has hit another new coronavirus infection record and hit a "critical juncture", according to the country's chief epidemiologist.
Dr Anders Tegnell has warned that pursuing herd immunity isn't ethical or justifiable after the country's Covid-19 cases ballooned by 70 per cent in a week.
The country, known for its light touch approach to the virus, recorded its highest number of infections for a second day in a row.
Authorities are now recommending residents of the capital, Stockholm, as well as those of two southern regions, limit contact with people and avoid enclosed spaces as Sweden registered an official record of 3254 new cases in one day.
People are being urged to avoid social interaction and going into shops, libraries and other closed public spaces.
Neighbouring Denmark has also made masks obligatory in enclosed public spaces.
"There has up to now been no infectious disease whose transmission was fully halted by herd immunity without a vaccine," Tegnell told Die Zeit, a German newspaper.
"Striving for herd immunity is neither ethical nor otherwise justifiable."
This goes against what the expert epidemiologist said back in May.
At that time, Tegnell told the Financial Times: "In the autumn there will be a second wave.
"Sweden will have a high level of immunity and the number of cases will probably be quite low. But Finland will have a very low level of immunity. Will Finland have to go into a complete lockdown again?"
That expected immunity doesn't appear to have been achieved though, with reports even back in June already indicating a low level of immunity in the community.
A study at that time, carried out by the country's Public Health Agency, found that only 6.1 per cent of the country's population had developed coronavirus antibodies by late May. This figure was far short of the 40 per cent predicted by Tegnell.
Now, the face of Sweden's virus response said the recent spikes in cases were partly the result of more intensive tracing and testing, but admitted there was also a greater spread of infection.
"We do have more new infections than we did in the summer and we're taking it very seriously," Tegnell said.
"But the curve is rising less steeply than elsewhere. So far the increase has not resulted in more people needing to be admitted to hospitals. All in all, we're fairly satisfied."
On Tuesday, Swedish authorities warned the situation was likely to get worse.
Its public health agency told residents in the northern Uppsala region to avoid public transport and not to meet people outside their household for two weeks.
The same advice has now been issued in the southernmost Scania region, but for a period of three weeks.
But while other countries struggling through a second wave of the virus are introducing mandatory restrictions, the measures in Sweden are only recommendations and not legally binding.
"This is a tough autumn and it will probably become worse before this is over," Tegnell told a news conference.
"Last week, the number of new cases increased by 70 per cent compared to the week before, one of the largest increases we've seen."
Sweden has famously refused the type of mandatory lockdowns seen elsewhere in Europe, preferring to appeal to people's sense of responsibility instead.
While polls show a majority of Swedes support such an approach, the strategy also has its detractors, both at home and abroad.
Some accused Sweden of playing Russian roulette with people's lives early on in the pandemic, as the death toll surged past those in neighbouring countries with stricter measures.
As of Friday, the country with a population of 10.3 million had recorded a total of 121,000 cases of Covid-19 and 5934 deaths.