An ambulance is seen in Oxford, Britain, April 24, 2020. A team at the University of Oxford is starting a coronavirus vaccine trial on humans Thursday. The team started work on developing the vaccine to prevent COVID-19 on Jan. 20, 2020. (Photo by Tim Ireland/Xinhua)

Researchers in hard-hit Brazil on Wednesday said they would begin testing a coronavirus vaccine developed in Britain, while across the Atlantic European nations began reopening borders in a bid to emerge from months of devastation caused by the disease.

Authorities in Brazil - the latest frontline of the pandemic, with deaths and infections on the rise - imposed fresh restrictions in the country's northeast after reporting "extremely high" numbers of cases.

Concern over the spread of the coronavirus in Latin America has increased even as the health crisis has eased in other regions of the world.

"The Americas continues to account for the most cases," World Health Organization (WHO) chief Tedros Adhanom Ghebreyesus said in a briefing in Geneva.

The UN body also said it would resume trials of hydroxychloroquine a week after halting them following a study in The Lancet medical journal that suggested the drug could harm COVID-19 patients.

The U-turn came after The Lancet itself cast doubt on the study after it was widely contested by scientists.

Another study published in the New England Journal of Medicine Wednesday suggested that taking hydroxychloroquine shortly after being exposed to COVID-19 does not help prevent infection in a statistically meaningful way, however.

The WHO has been holding clinical trials to find a treatment for COVID-19, which has killed more than 382,000 people and wrought vast economic damage since late 2019.

"We are especially worried about Central and South America, where many countries are witnessing accelerating epidemics," Tedros said.

Chile's government said it was extending a three-week shutdown of the capital Santiago and its population of 7 million as the death toll there reached a new daily record.

Health officials said 87 people had died in the previous 24 hours, and nearly 5,000 new infections were recorded. Chile has now registered more than 113,000 infections and 1,275 deaths. 

But outside of Latin America nations are cautiously reopening schools, beaches and businesses after months of quarantine, even as some still face rising numbers of cases.

European nations among the hardest hit by the outbreak have mostly flattened out infection curves. They have turned to the tricky task of balancing economic recovery against the risk of a second wave of cases.

Germany will plow 130 billion euros ($146 billion) into a stimulus package to kick-start an economy severely hit by the pandemic, Chancellor Angela Merkel announced.

Italy - the first country badly hit in Europe - opened its borders to European travelers Wednesday, hoping tourism will revive its recession-hit economy three months after its shutdown.

AFP