The developers of a coronavirus vaccine in Britain on Monday claimed success after mass testing, as the United States announced plans to give jabs to 20 million people before the end of the year to combat surging infections.
AstraZeneca and Oxford University said their drug had proved on average 70 percent effective at stopping the virus after trying it on 23,000 people, days after tests of two other drugs suggested they had more than 90 percent effectiveness.
The bright news on vaccines comes as Europe and the Americas battle rising caseloads that are pushing health systems to the brink, forcing governments to issue stay at home orders and close businesses even as the crucial Christmas period approaches.
Canada's biggest city Toronto will become the latest area to shut down later on Monday, as officials ban private indoor gatherings and limit the size of weddings and funerals -- similar to measures already in place in France and other European countries.
"We can't risk overwhelming our hospitals," said Doug Ford, premier of Ontario province, earlier this week.
At the other end of the confinement cycle, Australia's second-largest city Melbourne continued to emerge from a gruelling four-month lockdown with authorities lifting a ban on travel across state borders.
"When I went across the border I beeped the horn, 'Yahoo!'," said Melbourne resident Margaret Forster after being allowed to drive from Victoria into New South Wales for the first time since June.
The virus has killed almost 1.4 million people worldwide since emerging in China late last year.
- 'Immediate impact' -
The latest vaccine results are particularly important as the Oxford drug can be transported easily at normal refrigerator temperatures -- unlike some of the other candidates, which need extremely cold storage.
AstraZeneca chief executive Pascal Soriot said despite the vaccine's lower effectiveness compared with the other candidate drugs, it would still be highly effective and would have an "immediate impact".
The firm said it planned to develop up to three billion doses of the vaccine in 2021 if it passes the remaining regulatory hurdles.
Two other leading candidates -- one by Pfizer and German partner BioNTech and another by US firm Moderna -- reported 95 percent effectiveness in trials.
The European Union said it could approve vaccines for use by the end of the year, following a statement from US officials that a vaccination programme could be started as soon as next month.
"Our plan is to be able to ship vaccines to the immunization sites within 24 hours of approval," said Moncef Slaoui, head of the vaccine effort in the US, still the world's worst-hit nation with more than 12 million infections and 255,000 deaths.
The government's vaccine advisers will meet on December 10 to discuss approval.
Slaoui estimated that 20 million people across the US could be vaccinated in December, with 30 million per month after that.
But other experts stressed that Americans must continue to take precautions as many headed to airports to travel for this week's Thanksgiving holiday.
'Preparing for the worst'
Chinese officials were also facing a renewed threat, with a small outbreak at Shanghai's largest international airport.
All employees at the airport will now have to undergo testing after the cluster was linked to cargo handlers.
China has largely succeeded at tamping down its outbreak thanks to harsh lockdowns and rigorous test and trace programmes.
The country has also rolled out an experimental vaccine but its effectiveness is unclear.
Britain is still attempting to frame a clear policy after failing to develop a tracing app and even a top government adviser could not heed confinement orders.
Prime Minister Boris Johnson's latest plan is to roll out mass testing to the hardest-hit areas, hoping to make enough inroads to be able to relax social restrictions in time for Christmas.
Britain and the rest of Europe are facing up to the fact that the vaccines, even if they are approved, will not come online fast enough to deal with the current upsurge in cases.
Andreas Plemmenos, boss of a hospital near the Greek capital Athens, told AFP the latest wave of cases had arrived faster than expected.
"At the beginning, we only had three or four cases in this ward, but now it is full," he said of his dedicated 24-bed Covid-19 ward, which now has 10 new beds.
"We are preparing for the worst."