Sweden's top epidemiologist said on Tuesday a rapid decline in new critical COVID-19 cases alongside slowing death rates indicated that Sweden's strategy for slowing the epidemic, which has been widely questioned abroad, was working.

Sweden has foregone a hard lockdown throughout the outbreak, a strategy that set it apart from most of Europe.

Chief epidemiologist Anders Tegnell of the public health agency said a rapid slowdown in the spread of the virus indicated very strongly that Sweden had reached relatively widespread immunity.

"The epidemic is now being slowed down, in a way that I think few of us would have believed a week or so ago," he told a news conference.

Daily COVID-19 death rates as well as the number of infected in intensive care have been slowing gradually since April, with seven new deaths and no new ICU admissions reported by the health agency on Tuesday. Reported daily deaths peaked mid-April at 115.

"It really is yet another sign that the Swedish strategy is working," Tegnell said. It is possible to slow contagion fast with the measures we are taking in Sweden."

The slowdown in Sweden matched that in several countries that have accredited it to lockdowns. "We have managed to do it with substantially less invasive measures," he said.

Sweden's death toll of 5,646, when compared relative to population size, has far outstripped those of its Nordic neighbors, although it remains lower than in some European countries that locked down, such as Britain and Spain.