Sweden's state epidemiologist, Anders Tegnell, has received death threats over his handling of the pandemic, it was reported on Tuesday.
Swedish police are investigating threats made against Dr Tegnell and his family, the daily Aftonbladet newspaper reported.
He is considered by many to be the controversial mastermind behind the country's relatively relaxed coronavirus measures.
Dr Tegnell on Monday denied a claim that Stockholm was on course to achieve herd immunity, where a high enough percentage of the population developed resistance to the virus to stop it from spreading, by the end of the month.
“No, that will not happen,” he told US broadcaster NPR.
Dr Tegnell said he thought the immunity rate in the Swedish capital was still probably lower than 30 per cent.
“As you might be aware, there is a problem with measuring immunity for this virus,” he said.
A report released last week by Sweden’s public health agency containing the initial findings of a continuing antibody study showed only 7.3 per cent of people in the capital had developed antibodies to Covid-19.
Dr Tegnell is not alone in being threatened. Professor Christian Drosten, the director of the institute of virology at the Charite Hospital in Berlin and a member of the European Commission’s advisory panel on Covid-19, said in April that he, too, receives death threats, which he passes on to the police.
The revelation prompted Sir Jeremy Farrar, the director of the Wellcome Trust and a member of the UK’s Scientific Advisory Group for Emergencies (Sage), to post a Tweet in "solidarity", saying “many of us have received such threats”.
Sweden has been forced to defend its response to the coronavirus pandemic, rejecting “a week-by-week measurement of mortality” that shows the Scandinavian country as having one of the highest death rates in the world.
From May 12 to 19, Sweden reported 6.25 Covid-19 daily deaths for every million people across a seven-day rolling average, said Ourworldindata.org.
That was the highest in Europe, followed by Britain’s average of 5.75 deaths for every million people each day.
Swedish Foreign Minister Ann Linde stressed that “transmission is slowing down, the treatment of Covid-19 patients in intensive care is decreasing significantly and the rising death toll curve has been flattened".
“This is not a sprint, it’s a marathon,” Ms Linde said.
Sweden’s relatively soft approach to fighting the coronavirus attracted international attention.
Large gatherings were banned but restaurants and schools for younger children have stayed open.
The government has urged social distancing and Swedes have largely complied.
But the country has paid a heavy price, with more than 4,000 deaths from Covid-19.
That is about 40 deaths for every 100,000 of population, compared with about 10 in neighbouring Denmark and just over four in Norway, both of which imposed stricter lockdowns early on.
The coronavirus causes only mild or moderate symptoms in most people.
For some, especially older adults and people with existing health problems, it can cause more severe illness or death.