The rollout of AstraZeneca's Covid-19 vaccine, the shot much of the world is relying on to beat the pandemic, faced further complications on Thursday as India halted exports of the vaccine and Europe discussed its own export controls.
India has put a temporary hold on all major exports of the Anglo-Swedish firm's vaccine from the Serum Institute of India (SII), the world's biggest vaccine maker, to meet domestic demand as infections rise, two sources said.
That could delay supplies to dozens of lower-income countries also relying on SII production under the COVAX vaccine-sharing scheme backed by the World Health Organization.
"We understand that deliveries of Covid-19 vaccines to lower-income economies participating in the COVAX facility will likely face delays...," the programme's procurement and distributing partner UNICEF told Reuters.
India's move comes as the European Union meets on Thursday to consider giving member states greater scope to block vaccines being exported outside the bloc, much of which is struggling to bring infections down and ramp up immunisation campaigns.
The proposal would apply to all vaccines including AstraZeneca's, on which the EU had originally been relying to meet a goal of inoculating 70% of its adult population by this summer.
AstraZeneca's vaccine is seen as crucial in tackling the pandemic as it is cheaper and easier to transport than many rival shots.
The EU accuses the drugmaker of over-selling its vaccine and unfairly favouring Britain, where AstraZeneca developed the shot with Oxford University - a charge denied by the company.
Brussels agreed with London this week to strive for a "win-win" solution, but even if the EU resists export controls, it faces another problem: declining confidence in the AstraZeneca shot due to concerns over side-effects and efficacy data.
Denmark will suspend its use of the vaccine for another three weeks pending further investigations into a potential link between the vaccine and blood clots, Danish broadcaster TV 2 reported on Thursday, citing sources.
More than 10 other nations also suspended rollout of the vaccine over similar concerns but most have since restarted. The European Medicines Agency said last week it was safe and not linked with a rise in overall risk of blood clots.
However, many Europeans remain wary.
A third of Danes would refuse the AstraZeneca vaccine, according to a survey published by Danish media on Wednesday. Confidence has also taken a big hit in Spain, Germany, France and Italy.
AstraZeneca revised down, slightly, the vaccine's efficacy to 76% in a new analysis of its US trial. Interim data published on Monday had put the vaccine's efficacy rate at 79% but had not included more recent infections, leading to a highly unusual public rebuke from U.S health officials.
AstraZeneca, which is awaiting US regulatory approval, also reiterated the shot was 100% effective against severe or critical forms of Covid-19.
"The vaccine efficacy against severe disease, including death, puts the AZ vaccine in the same ballpark as the other vaccines," said William Schaffner, an infectious disease expert from the Vanderbilt University School of Medicine, adding he expects the shot to gain US approval.
The vaccine has already been granted conditional marketing or emergency use authorisation in more than 70 countries.
In Europe, the leaders of France and Germany admitted on Thursday that the problem of slow vaccine rollouts inside the EU went beyond the question of whether to control exports.
German Chancellor Angela Merkel said EU leaders would also discuss how to boost internal production of vaccines.
"British production sites are manufacturing for Britain and the United States is not exporting, so we are reliant on what we can make in Europe," she told German lawmakers.
French President Emmanuel Macron said the EU itself should take some blame - that its vaccine plans had lacked ambition.
"We didn't shoot for the stars," he told Greek television channel ERT. "That should be a lesson for all of us."