The United States on Friday recorded its steepest job losses in history over the coronavirus pandemic as Europe, faced with rising deaths, moved to keep its borders shut for another month.

Hopes have been rising that the worst of the global catastrophe, which has killed more than 270,000 people, has passed, and the United States on Friday approved a new at-home saliva test to speed up diagnosis for COVID-19.

But after weeks in which half of humanity was restricted from carrying on normal life, the effects have been painfully visible, with the global economy suffering its most acute downturn in nearly a century.

In the United States, 20.5 million jobs were wiped out in April -- the most ever reported -- with unemployment rising to 14.7 per cent, the highest since the Great Depression.

The world's largest economy has suffered the deadliest coronavirus outbreak, with more than 77,000 fatalities and nearly 1.3 million cases.

Mindful of elections in November, President Donald Trump has nonetheless vowed to reopen the country, and a growing number of state governors have already let business resume with precautions.

Trump played down the unemployment numbers, saying they were expected, as the White House pointed to substantial gains Friday on global stock markets as proof that better times were ahead.

"We're going to have a phenomenal year next year," Trump told reporters. "I think it's going to come back blazing."

His optimism came even as the virus spread within the White House, with the press secretary of Vice President Mike Pence testing positive.

Neighboring Canada also shed three million jobs, bringing its unemployment rate up to 13.1 percent, two days after the European Union forecast a massive recession in the bloc.