EU said it was confident in meeting its goal of vaccinating 70% of adults by the end of the summer
The United States hailed progress in turning around its troubled Covid-19 vaccine rollout, as the European Union said it was on track to meet jab targets and Asia's inoculation drive gained pace on Friday.
Brazil hit over 251,000 fatalities -- the second-highest national death toll after the United States -- while the worldwide vaccine campaign received the endorsement of Queen Elizabeth II, 94, who urged people not to be wary of the shot.
President Joe Biden declared the US rollout is now "weeks ahead of schedule" as he celebrated 50 million doses administered since he took office on January 20, but he warned Americans to keep masking up.
"We're moving in the right direction despite the mess we inherited," Biden said, referring to the program under his predecessor Donald Trump.
The United States is the world's hardest-hit country, with coronavirus deaths crossing the 500,000 mark earlier this week.
Rollouts in Asia also gathered momentum as Hong Kong and South Korea began their mass vaccination programs on Friday.
Both places were among the first to experience outbreaks after the coronavirus spread from central China early last year, but have kept infections comparatively low.
South Korea plans to inoculate 70% of its population within seven months while Hong Kong aims to vaccinate all adults by the end of the year.
And after months of supply problems and friction, the EU said on Thursday it was confident in meeting its goal of vaccinating 70% of adults by the end of the summer.
Cases top 113.6 million
The coronavirus has killed more than 2.5 million people worldwide, with nearly 114 million known infections, and vaccine rollouts have been patchy.
Most of the 217 million doses administered globally have gone to wealthier countries, and among those struggling with shortages is Brazil.
The South American nation crossed a quarter-million death toll on Thursday as it battles a devastating second wave of infections.
The coronavirus has hit especially hard in Brazil's impoverished "favelas," among indigenous communities and in the Amazon rainforest city of Manaus, where there have been haunting scenes of mass graves and patients suffocating to death with no oxygen.
There was also worrying news on Friday out of impoverished Papua New Guinea, which reported its largest daily jump in cases since the pandemic began, with infections spreading to remote regions with poor health infrastructure.
But efforts to ensure wider availability of vaccines were given a boost when the US Food and Drug Administration said frozen vials of the Pfizer-BioNTech vaccine may be stored at temperatures commonly found in pharmaceutical freezers -- instead of specialized ultracold ones -- for up to two weeks.
Meanwhile, finance ministers and central bankers of the G20 countries -- which account for 80% of world trade -- meet to align plans to relaunch the global economy after the pandemic and limit harm to worst-off nations shut out of the race for vaccines.