The WHO said on Wednesday that, where the epidemic was spreading, people - including children and students aged 12 or over - should always wear masks in shops, workplaces and schools that lack adequate ventilation and when receiving visitors at home in poorly ventilated rooms.

However, the Swedish Health Agency, largely behind Sweden's no-lockdown strategy, has refrained from recommending masks, citing poor evidence of their effectiveness and fears that masks might be used as an excuse to not isolate when experiencing symptoms.

"Face masks may be needed in some situations. Those situations have not arisen in Sweden yet, according to our dialogue with the (healthcare) regions," Sweden's chief epidemiologist Anders Tegnell told a news conference on Thursday.

"WHO is clear that the state of evidence for masks is weak. All studies so far suggest that it is much more important to keep your distance than to have a face mask," he said.

In a bid to stem a severe second wave, Prime Minister Stefan Lofven announced on Thursday that high schools would switch to distance learning for the rest of the year.

Sweden registered 35 new COVID-19 related deaths on Thursday, taking the total to 7007.

The country also registered 6485 new coronavirus cases on Thursday.

That compared with a high of 7240 daily cases recorded two weeks ago.

Sweden's death rate per capita is several times higher than that of its Nordic neighbours but lower than several European countries that opted for lockdowns.

Australian Associated Press