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What's the story?
While the UK’s vaccine rollout has surpassed all expectations and immunised more than half of British adults, the same is not true of the efforts of our European cousins.
EU politicians and diplomats are under extreme pressure to explain to voters why the bloc has managed to vaccinate barely 12 per cent of its eligible population, while it continues to export millions of doses of different vaccines abroad.
European leaders will use a crunch meeting on Thursday to take steps to prevent vaccines (or their ingredients) being exported to countries that have their own manufacturing capability and a strong vaccine drive.
The plans, announced in a press conference on Wednesday, could mean the supply of jabs to Britain is restricted, which some believe could put the UK’s vaccine rollout back by two months.
So far around 10 million vaccines, mostly from Pfizer, have been sent from the Continent to the UK.
Much of the recent anger in Brussels has been directed towards AstraZeneca, which has signed contracts with the UK that give Britain priority over the first 100 million vaccines the company produces, in exchange for R&D funding from the UK Government in the early stages of the pandemic.
The company says it has been hit with supply issues, and while it is legally bound to protect the doses destined for Britain, its EU contract only demands its “best reasonable efforts”.
So AstraZeneca jabs produced abroad have been sent to the UK, while doses manufactured in Britain have stayed here. As a result, the company has delivered just 30 per cent of the doses promised in its EU contract for the first quarter of 2021.
Watch: Brussels tightens vaccine export rules to ensure jabs stay in the bloc
Ursula von der Leyen, the President of the European Commission, had initially planned to keep vaccines in the EU by using an obscure legal mechanism buried in the Lisbon Treaty, which allows officials to take control of factories and re-route the jabs to European arms.
Now it seems the latest plans would only be triggered if the country receiving the vaccines had a strong vaccine rollout programme and its own manufacturing plants.
In a press conference on Wednesday, officials introduced the concepts of "reciprocity and proportionality".
"Open roads should run in both directions," Ms von der Leyen said.
That loosely translates to: Does the country of destination need jabs more than the EU? And does the EU get anything back?
This is not the first time that EU leaders have found themselves in hot water over the AstraZeneca jab.
In January, the EU approved export restrictions on vaccines, but they can only be used if the company is not fulfilling its contractual obligations with the EU, and if the country where the vaccines are headed is not considered vulnerable. So the controls haven’t been used yet, and they expire this month.
Meanwhile, European politicians themselves have seriously undermined public trust in the AstraZeneca vaccine by suggesting publicly that it does not work in the elderly population, or that it may increase the risk of blood clots.
Emmanuel Macron has withdrawn his earlier comments about the use of the jab in the over-65s – but polling suggests the majority of the population in many EU states now don’t trust the AstraZeneca vaccine, and may turn it down if one was offered.
That could later be an issue for the EU, as the AstraZeneca vaccine is easier to transport and store, cheaper to manufacture and could be the answer to the bloc’s ailing rollout effort.
The pressure on European politicians is exacerbated by what looks like a third wave of coronavirus cases on the Continent, which could significantly raise the death rate there if more people are not jabbed soon.
The latest row centres on the export of jabs from a specific factory contracted to manufacture AstraZeneca jabs in Leiden, in the Netherlands.
Boris Johnson has indicated that the UK would be willing to share the output of that factory with the EU, but the Commission wants access to vaccines produced in factories in Britain too.
Ms von der Leyen has called for “reciprocity” of vaccine exports, while a diplomat painted the EU as the “pharmacist of the world,” merrily handing out jabs to 33 countries while its own people miss out.
The UK is unlikely to give up any jabs manufactured in Britain, at risk of slowing down its rollout programme and squandering the opportunity to end lockdown sooner.
Mr Johnson has said that the UK thinks any contracts signed should be respected – which is a way of saying that Britain is happy to continue to receive preferential treatment in exchange for its early support of the AstraZeneca jab and the hard negotiating of the UK vaccines taskforce.
The stern words on both sides of the Channel are reminiscent of endless debates over Brexit, but in this round of talks the EU has no need to keep British voters and the Eurosceptic media on side. EU diplomats have been privately briefing journalists that all the Commission wants is “fairness” and views the issue as a problem with AstraZeneca, rather than with the UK.
Several EU figures, including Micheal Martin, the Irish Prime Minister, have said they would prefer to avoid a ban altogether and work out the supply issues through negotiation.
But if officials move to block vaccines that would otherwise have been administered in Britain, Government sources say the UK could retaliate with bans on its own exports to the EU in a “tit-for-tat” move.
That would see relations between Britain and its neighbours break down even further.
This political debate is viewed with exasperation from scientists and health officials, who point out that everyone will eventually need to be vaccinated anyway because the virus travels across borders.
But UK officials know that any threat to the vaccine drive risks delaying the timetable for the end of lockdown, which is set to be completely eased by June 21.
Other issues with supply – notably from a factory in India – have increased the pressure on ministers to keep the vaccine effort on track and the exports from the EU rolling.
With Britain passing a year since the first lockdown this week, the political price for letting the roadmap slip will be extremely high.
Mr Johnson has spent the last four years telling the electorate that the UK can be more successful when it is independent from Europe. Now he has the chance to prove it.
Watch: Key moments in the 12 months since the UK’s first lockdown