WASHINGTON: The United States on Thursday hailed progress in turning around its troubled Covid-19 vaccine rollout, and the European Union said it was also on track to meet jab targets as global coronavirus deaths topped 2.5 million.

Brazil hit 250,000 fatalities -- the second-highest national death toll after the US -- while the worldwide vaccine campaign received the royal endorsement of Queen Elizabeth II, 94, who urged people not to be wary of the injection.

President Joe Biden declared the US rollout is now "weeks ahead of schedule" as he celebrated 50 million vaccines 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.

Biden said that there would be "enough supply" for all adult Americans by the end of July.

The EU announced Thursday it expected to vaccinate 70 percent of adults by the end of the summer, after months of problems and friction.

European Commission chief Ursula von der Leyen said fully vaccinating just under three-quarters of adults by late summer was a "goal that we're confident with."

But in Brazil, the grim quarter-million deaths milestone came one year after the first Covid-19 case was confirmed in the country, which is struggling with severe vaccine shortages and a devastating second wave.

Mass graves

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.

President Jair Bolsonaro has flouted expert advice on managing the pandemic, railing against lockdowns and face masks and instead touting the malaria drug hydroxychloroquine, despite studies showing it is ineffective against Covid-19.

Britain's Queen Elizabeth said in a video message Thursday that her coronavirus jab "didn't hurt at all" and encouraged those reluctant about receiving the vaccine to "think about other people."

The monarch was vaccinated along with her husband Prince Philip in January.

In total, 2,500,172 deaths and 112,618,488 cases have been reported, with almost half of the fatalities occurring in just five countries: the United States, Brazil, Mexico, India and Britain, according to an AFP count based on official figures.

In China, where the virus first emerged in late 2019, the national drug authority approved two more vaccines made by domestic companies for public use, bringing the number of Chinese vaccines to four.

Two Cuban vaccines will undergo advanced clinical trials from March after they reportedly elicited a "powerful immune response" in early tests, one of the scientists in charge of the project said Thursday.

Focus on long-term symptoms

In further vaccine developments, frozen vials of Pfizer's Covid-19 vaccine may be stored at temperatures commonly found in pharmaceutical freezers for up to two weeks, the US Food and Drug Administration said Thursday.

The move loosens a previous requirement that the vaccine should be stored at ultra-low temperatures, between -112 and -76 degrees Fahrenheit (-80 to -60 degrees Celsius).

The World Health Organization (WHO), meanwhile, urged governments to try to better understand the long-term consequences of coronavirus on some sufferers who have prolonged symptoms such as tiredness, brain fog, and cardiac and neurological disorders.

"It's a clear priority for WHO, and of the utmost importance. It should be for every health authority," said Hans Kluge, regional director for WHO Europe.

Britain, which has forged ahead with its vaccine drive, said Thursday it was lowering its alert level from the highest tier, citing a dip in cases.

In France, hopes of a return to normal on the sports front were dashed after more than a dozen rugby players and staff tested positive, forcing Sunday's Six Nations match against Scotland to be scrapped.

In another sign of the toll the pandemic is taking on populations, the number of babies born in France in January also fell by 13 percent, the biggest drop in 45 years.

And in Japan, organisers of the delayed Olympic torch relay said fans could line the route when it kicks off next month, but cheering is strictly banned and social distancing will be enforced.

Some sex workers in Bangladesh's largest brothel started getting their vaccines, a health official said Thursday.

Beauty, 40, who goes by one name, said she was initially hesitant about getting the shot.

"But the health officials reassured us. Now we understand it is important as we meet many people every day," she said.

Syria will start giving coronavirus vaccines to its healthcare workers across the war-ravaged country from next week.