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Earlier this month, more than a dozen European countries paused the rollout of the Oxford-AstraZeneca Covid-19 vaccine following reports of blood clots in people who had received it. Then, almost as quickly as it had been suspended, the rollout started again. But this short-lived delay, which covered much of Europe, may have significant repercussions: both time lost in the vaccine rollout and the blow to the already-fragile vaccine confidence levels in these countries.
All of the debate around the suspensions hung on one issue: whether the clots were caused by the vaccine or whether they occurred coincidentally around the same time. Blood clotting events happen everyday, and if you vaccinate enough people, it’s inevitable that some of those will be in people who received the vaccine. According to AstraZeneca, among the 17 million people across Europe who have had the jab, there have been 37 reports of blood clots, as of March 8. About one adult in every 1,000 suffers a deep vein thrombosis each year. That means that 37 out of 17 million people is an incidence rate that actually appears to be lower than would be expected.
The reporting of adverse events following rollout of mass vaccination programmes is to be expected, and is a good thing. Other side effects people have reported after receiving the Oxford-AstraZeneca vaccine include: flatulence, diet failure, crying, excessive earwax production and anal itch. While keeping track of reported side effects helps health authorities know what to expect, many of the adverse events will not be caused by the vaccine itself. Deciding when to rightly press pause when a legitimate cause for concern arises – and to decide against it if it seems to be a false alarm – is crucial.
So, if the number of blood clots is lower than would be expected, why did so many countries decide to suspend the vaccine’s use?
The decision was ostensibly made on the basis of the precautionary principle – taking anticipatory action to avoid potential harm, even when evidence supporting that harm is not certain. European health authorities exercised use of the principle in order to provide reassurance to the public that the vaccine is safe. But it could be argued that that the principle was misapplied – that the dent in vaccine confidence will ultimately lead to an even higher risk for the public than blood clots: a concerningly low vaccine take-up.
A more worrying scenario in Germany complicates things. German health authorities suspended the AstraZeneca vaccine after seven cases of cerebral venous thrombosis were reported amongst the 1.6 million people who have received the jab, of which three have died. Six of the people had a particular form of cerebral venous thrombosis, called cerebral sinus vein thrombosis. Incidences of cerebral sinus vein thrombosis in a normal population, though difficult to measure, are thought to be pretty rare: around five people in a million die every year. Therefore, Germany’s number of cases have exceeded normal expectations: in a vaccination population of this size, only one case of this type of blood clot would have been expected to occur by chance. This makes the incidences more difficult to dismiss out of hand. For now, the European Medicines Agency has said the evidence is not conclusive as to whether it is related to the vaccine, and that it will continue to gather information and studies on the condition.
Going forward, rather than the suspension bolstering confidence in the vaccine – as health authorities maintain was the intention – it’s likely it will have the opposite effect amongst the public in these countries, says Jonathan Kennedy, a lecturer in global public health at Queen Mary University of London. “Vaccine confidence was already remarkably low in Europe before coronavirus struck,” he says. The biggest driver of this distrust were concerns about safety, and the idea that the state and pharmaceutical companies were hiding evidence of dangerous side effects.
As to whether Kennedy thinks that the damage in vaccine confidence will be irreparable, he says that although vaccine confidence fluctuates over time and varies between jabs, it will be “very difficult for the AstraZeneca vaccine to recover”.
According to a study conducted by the RECOVER Social Sciences team into public views of Covid-19 vaccines in seven European countries, including France, Germany, Italy and Spain, less than 40 per cent of those surveyed strongly agree with the statement that vaccines are safe.
A poll published by the Elabe Institute, a French research and consultancy firm, found that that only 20 per cent of French people now trust the AstraZeneca vaccine, and 58 per cent do not trust it, with 22 per cent undecided. In a recent preprint, vaccine confidence in Denmark was shown to have dropped by about 11 per cent following the country’s decision to suspend use of the jab.
The incident will likely sink vaccination rates even lower in these countries, which were already struggling to vaccinate their populations. Less than ten per cent of EU citizens over 18 have received their first dose, as of March 14. Over 12 million vaccine doses are currently unused. Skepticism towards the AstraZeneca vaccine has lingered ever since a slew of countries ceased use of the jab in people over the age of 65 due to the lack of evidence of its efficacy in older people. Utilisation rate of the vaccine stood at 24 per cent in France as of February 28, according to the country’s health ministry.
“Ultimately, it can’t do anything other than suppress take-up of the vaccine,” says Paul Hunter, a professor of medicine at the University of East Anglia. “And as a result, people will succumb [to the virus] when they would otherwise have not.” He gives the example of a man in his mid-40s, who will have a one in 1,000 chance of dying if he gets Covid-19. If a million men in their mid-40s decide not to get the vaccine, and about half of them contract Covid-19, that would result in about 500 deaths.
As much of Europe heads into a third wave, the fallout from this setback could be devastating. “Thousands of people are still dying every day from Covid in Europe,” says Kennedy. “It will be a public health disaster if millions of unwanted doses are stuck in warehouses in Germany and France while people wait for what they believe is a better vaccine. Ultimately, any vaccine is better than no vaccine.”
Grace Browne is a science writer at WIRED. She tweets from @gracefbrowne
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