Europe's row with AstraZeneca worsened after Germany declined to recommend the firm's coronavirus vaccine for older people, while the more contagious South African variant of the virus was detected for the first time in the already hard-hit United States.
With anti-virus restrictions being tightened worldwide again, the economic toll came into focus with the United States seeing its sharpest contraction in growth since 1946.
UN data released on Thursday also said the global tourism sector, battered by border closures and bans on mass gatherings, lost $1.3 trillion in revenue in 2020.
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Given the world's weariness over the pandemic that has now killed some 2.2 million people and infected more than 100 million, countries have been anxious to expedite vaccination campaigns.
There was encouraging news from US biotech firm Novavax, which said its two-shot vaccine showed an overall efficacy of 89.3 percent in a major Phase 3 clinical trial in Britain, and remained highly effective against a variant first identified there.
But other results showed it offered significantly less protection against a highly transmissible virus variant first identified in South Africa, which is spreading rapidly around the world.
The European Union's inoculation efforts were hit by an announcement from AstraZeneca that it could only supply a quarter of the doses it had promised for the first quarter of 2021.
The EU has demanded the drug maker meets its commitments by supplying doses from its UK factories, but Britain insists it must receive all of the vaccines it ordered.
Adding to the row on Thursday was an announcement from Germany's vaccine commission that it could not recommend AstraZeneca's vaccine for those over 65 since there was not enough data to assess its efficacy.
AstraZeneca and British Prime Minister Boris Johnson immediately defended the vaccine, which has already been widely used in Britain on older people.
The European Medicines Agency is expected on Friday to announce whether to recommend authorisation of AstraZeneca's shot. The regulator has already approved the Pfizer-BioNTech and Moderna vaccines.
- Variant worries -
Covid-19 has killed more than 432,000 in America, by far the highest absolute toll, and more troubling news came Thursday when authorities announced they had found two people in South Carolina infected with the strain first detected in South Africa.
Scientists are worried about this mutation because it seems able to elude some of the effects of current vaccines and synthetic antibody treatments, though Moderna and Pfizer said their shots still work against the variant.
A more contagious form of the virus could nonetheless mean more people get sick, a portion of whom could end up hospitalised or in the most severe cases dead.
In the Americas overall, 14 countries have reported at least one of three coronavirus variants -- first detected in Britain, South Africa and Brazil -- the Pan American Health Organization said Thursday.
The economic pain over the last year in the US was clear in data out Thursday that showed the world's largest economy shrunk by 3.5 percent in 2020.
The figures underscored the scale of the job awaiting President Joe Biden, who took office just over a week ago promising to get the country back on track with a $1.9 trillion spending proposal.
At the same time, a long-delayed effort to probe the virus's origins creaked forward for a World Health Organization team of experts in Wuhan, China.
- India's vaccine diplomacy -
Covid has continued to hammer countries despite the onset of mass vaccination programmes that have seen more than 82 million doses injected, according to an AFP count compiled from national figures.
Pfizer has also faced EU criticism for delays in deliveries but has now revised its production target for this year up from 1.3 billion doses to two billion.
Australia's health minister Greg Hunt said the country's foreign ministry would be making "representations" to the EU on suggestions there may be restrictions on vaccine exports.
Those representations would be about "ensuring that our supply is guaranteed on a continuous basis," he said.
Meanwhile, Indian Prime Minister Narendra Modi said his country will supply more locally produced vaccines to other countries.
India -- home to the world's largest vaccine manufacturer, the Serum Institute -- has embarked on a form of vaccine diplomacy, gifting millions of doses to its neighbours.
Concerns have been deepening over rich nations hogging vaccine supplies. The WHO said Thursday that Africa can expect to see at least 30 percent of its population immunised by the end of this year.Follow our full coverage of the coronavirus pandemic here.