t has been a disquieting week for those concerned about the lifting of Covid restrictions. Numbers of cases and deaths may be declining but the news that the AstraZeneca vaccine has been linked to cases of rare blood clots and has been suspended for use in younger people in Germany and the Netherlands is a disturbing development. The AstraZeneca jab is the prime hope we have of clearing Britain of this disease and is now, once again, under hostile scrutiny. Not for the first time, this vaccine has become enmeshed in geopolitics and its usefulness questioned. It is a grim story. In this case, fears have been raised that the vaccine may be linked to seven deaths among a total of 30 rare blood-clotting cases that arose after administration of the vaccine. That is of obvious concern, but a quick look at the arithmetic puts those fears into perspective. Those 30 cases occurred among 18 million recipients of the AstraZeneca jab, a risk of less than one in 500,000. Now run this simple thought experiment and ask what would happen if we stopped the vaccination of 500,000 middle-aged people, say, for a month? About 85 would be hospitalised and about five would die from Covid, it is estimated. Those figures reveal the power of vaccinations that have already prevented more than 6,000 Covid deaths in the UK, with tens of thousands of lives likely to be saved this year. Nor is it clear a causal link exists between the AstraZeneca vaccine and clots (of which most are a variety called cerebral sinus venous thrombosis, CSVT). However, even if such a connection exists, we should note that among Covid’s many impacts, clotting events are included. Crucially, the chances of getting a clot through infection with the Covid virus are several orders of magnitude more likely than are the chances of getting a clot from the vaccine. Hence the robust defence of the AstraZeneca vaccine by most UK doctors and scientists. Nevertheless, swaths of Europe continue to restrict its use at a time when many nations are suffering third waves of Covid-19 cases and have said they are desperate for vaccine supplies. It is a baffling response. Consider Germany. It initially decided not to give the AstraZeneca vaccine to elderly people because of safety fears. Then it approved it for all its citizens. And then Germany changed its mind again last week and plumped for giving it only to the elderly and to refuse its use for younger people. Such vacillation is absurd and harmful. Public confidence in vaccines will be crucial in extricating the world from its Covid nightmare. The signals sent by Germany – and the Netherlands and many other European nations – are worrying. In the UK, it has triggered fears among senior public health officials that growing numbers of younger people, particularly women who have raised risks of developing these blood clots, may shun the AstraZeneca jab. It is the one approved vaccine that can be easily shipped and does not need complicated refrigeration. But if its safety is constantly undermined by individual national regulators across Europe, developing countries will be hesitant to use it. Why should they accept a vaccine at which western society turns up its nose? Just why the AstraZeneca vaccine has been subject to constant undermining is hard to determine. Kate Bingham, who led Britain’s highly successful Vaccine Taskforce, has described the UK-Swedish company as “heroes” for the way it stepped up to provide a safe, effective, easily deployed vaccine, first developed at Oxford University, and indicated her regret that it has been “caught up in geopolitics”. Certainly, it is strange that the one vaccine to be sold at cost price, and which has eschewed the typical high-pricing plans of big pharma, is the one that has been subjected to the greatest vilification. The world needs – as a matter of urgency – more than 11bn doses of vaccine to provide the 5.8 billion adults on our planet with double jabs that will free humanity from Covid-19, with further doses needed in future to counter virus variants. To date, more than 600m doses have been administered. The 3bn doses that have been promised by AstraZeneca this year will make a huge difference in protecting humanity. Yet it is being shunned for questionable motives. It might be tempting to indulge in a bout of vaccine schadenfreude. Once derided for its initial Covid responses – late lockdowns, poor test-and-trace programmes – the UK has triumphed with its vaccine rollout programme while the EU has floundered. But as Covid continues to spread across Europe, Britain’s borders will have to remain closed. As the slogan goes: nobody is safe until everyone is safe. It’s trite but right and that is why we need all the vaccines we can get. Forty years ago, when the Aids zoonotic pandemic first appeared, it took scientists four years to develop a test that could determine if people were infected, a crucial first step if you want to track and contain a disease. With Covid-19, scientists developed a test in less than a month, while vaccines were approved within a year. Dramatic scientific improvements have made it possible to survive this pandemic, and not just in medicine. Without Zoom calls, PCR testing, the internet and genome sequencing, our global lockdown would have been impossible. The trouble is that science and technology on their own are inadequate for tackling catastrophes such as Covid-19. The world also needs politicians, health services and civil services that can use these gifts with skill and wisdom. Supplies of these attributes have been inconsistent in most western countries. Britain has done well with its current massive, rapid vaccine rollout but that is no guarantee it will not return to the chaos of last year’s Covid responses. We are not yet out of trouble. Robin McKie is science and environment editor for the Observer