The AstraZeneca shot is cheaper and easier to store than many of its rivals, but its use was thrown into chaos when several nations in Europe and other parts of the world last week suspended their rollouts because of isolated cases of blood clots.
Vaccination drives are seen as crucial to overcoming the pandemic that has killed more than 2.7 million people since first emerging in China in late 2019.
They are also the most likely route out of lockdowns and restrictions that continue to paralyse economies, with frustrated crowds in several cities in Europe protesting against the curbs over the weekend.
Britain has doled out more than 11 million of the jabs developed by Anglo-Swedish company AstraZeneca and Oxford University, but public confidence has been damaged in EU countries.
A survey by British pollsters YouGov showed yesterday that a majority of people in the biggest EU states - including Germany, France, Spain and Italy - view the vaccine as unsafe.
The EU’s regulator and the World Health Organization have however deemed it safe and said there is no evidence of a link between the drug and the blood clots, leading countries including France and Germany to resume vaccinations.
And AstraZeneca said Monday that US tests on more than 30,000 people showed no increased risk of thrombosis.
It said the jab was 79% effective at preventing symptomatic COVID-19 in the overall population, 100% effective at preventing severe disease and hospitalisation and 80% effective at preventing the disease in the elderly.
“This analysis validates the AstraZeneca COVID-19 vaccine as a much-needed additional vaccination option,” said Ann Falsey, a professor responsible for the trial.
The company is preparing to submit its findings to the US Food and Drug Administration to authorize the shot for emergency use.
‘We vaccinated, baby’
More than 430 million jabs have now been rolled out around the world, with the US accounting for more than a quarter.
The US remains the worst affected country overall, but the acceleration of its inoculation campaign has led to a celebratory mood, particularly in Miami where students were gathering in force to celebrate spring break.
“Just go get your vaccine y’all, so that you could come out here and have a good time like us because we vaccinated, baby,” Jalen Rob, a student from Texas, told AFP.
But US health expert Anthony Fauci stressed that people still needed to remain cautious or face more infection spikes.
Mass gatherings were also giving governments a headache in Europe, where protesters took to the streets against virus restrictions in Germany, the Netherlands, Austria and Bulgaria.
In the French Mediterranean port city of Marseille, roughly 6,500 people - mostly young and mostly without masks - took part in a carnival parade, flouting a ban on public gatherings.
“Nothing justifies that we undermine our collective efforts to keep the virus at bay,” said Marseille mayor Benoit Payan, adding that he was “outraged” by the event.
But Indian officials were perhaps facing the biggest challenge, with a month-long Hindu festival attracting more than three million pilgrims in one day earlier this month.
The government warned that it could turn into a superspreader event and urged local officials in Uttarkhand to enforce strict protocols.
‘Everything has evaporated’
Despite vaccine rollouts, the contagion appears to be spreading faster, with new infections up globally by 14% in the past week.
Germany, Europe’s biggest economy, is poised to prolong restrictions and tighten a partial lockdown into April, according to a draft document seen by AFP.
But politicians and vaccine makers continue to put forward optimistic outlooks, with the backer of Russia’s Sputnik V jab saying an Indian manufacturer had agreed to produce 200 million doses every year.
EU commissioner Thierry Breton suggested that the whole continent could have immunity by July 14.
“We’re in the home stretch, because we know that to beat this pandemic there’s just one solution: vaccination. The vaccines are arriving,” he said.
Yet the EU is engaged in an escalating spat with the UK over vaccines. The bloc has threatened to ban exports of the AstraZeneca shot across the English Channel, which could lead to a tit-for-tat dispute that would damage supply lines on both sides.
Many countries in Africa are struggling with the rollout and with health systems ill-equipped to deal with the pandemic - underlined by the death of an opposition politician in Republic of Congo who was being transferred to France for treatment.
Japan, which has been relatively untouched by the virus, has not been insulated from the economic effects of restrictions.
Business owners are counting the cost of a decision to ban overseas fans from this summer’s Olympic Games.
“I was thinking, ‘Next year with the Olympics, everything is going to be going up and up’,” Toshiko Ishii, who spent $180,000 (B5.5 million) renovating her traditional Japanese inn, told AFP. “Now all of a sudden everything has evaporated.”