We should take confidence from the fact the advice on the AstraZeneca jab has moved with the data
If the presentations led by medical regulators in the UK and Europe on Wednesday do not build confidence in vaccines I’m not sure what will. Performing under pressure, they managed that rare feat: treating us as adults and communicating their all-but-matching messages with clarity.
The key message is this: the benefits of taking the AstraZeneca vaccine greatly outweigh the “serious but vanishingly rare” clotting risk associated with it. Only for the young – those under 30 – is the judgment more “finely tuned”, and even then the vaccine continues to trump the risk of Covid while the virus is widespread (see charts below).
In large parts of Europe and Canada, younger cohorts are already being offered alternative jabs and the UK is now following suit, offering all those under 30 a choice “where an alternative vaccine is available”.
The UK’s Vaccine Taskforce invested early in a “balanced portfolio” of vaccinations and that flexibility is now being put to good use.
We don’t notice it in normal times but this is very much business as usual in healthcare. For many vaccines and medicines, there are a variety of alternatives, all with different pros and cons, and doctors administer them to different groups as appropriate.
The deputy chief medical officer, Professor Jonathan Van Tam, went to some lengths to point out that the shift in policy amounts to a “course correction” and he was right to do so. Our trust in regulators – and science – hinges on their ability to change course when the evidence demands it and this is exactly what has been done in difficult circumstances.
“This is a massive beast that we are driving along at enormous pace with enormous success, this vaccine programme,” said Prof Van Tam. “If you sail a massive liner across the Atlantic then it’s not really reasonable that you aren’t going to have to make at least one course correction during that voyage.”
He could have added that the fate of the Titanic is a testament to what happens if you ignore a change in circumstances.
So what are the risks associated with the AstraZeneca jab? Unfortunately, that is still not clear and is unlikely to be for some time. The blood clotting side effect is so rare that there is still not enough data to pin down its true incidence with confidence.
“Based on the current available evidence, specific risk factors such as age, gender, or previous medical history of clotting disorders have not been able to be confirmed, as the rare events are seen in all ages, and in men and women,” said the European Medicines Agency (EMA).
According to the UK’s Medicine and Healthcare Products Regulatory Agency (MHRA), 20 million AstraZeneca jabs were administered in the UK up to March 31 and 79 cases of rare blood clots were reported. Of these, 19 people died, three of whom were under 30. This equates to about four cases in a million (one in 250,000), said Professor June Raine, head of the MHRA.
The EMA, while hesitant of drawing firm conclusions, suggested the risk was likely to be higher.
As of April 4, its drug safety database had received a total of 222 reports of rare clots out of 34 million AstraZeneca vaccinations. That works out at about seven cases per million but Dr Sabine Straus of the EMA thought the real incidence might be more like “one in 100,000” after taking into account under-reporting.
Even at that level, the risks are low compared to the risk of Covid-19 for all but the young. Oxford University’s QCovid risk calculator enables individuals to see their personal risk of being hospitalised or dying of Covid-19 during a surge of the virus.
For all age groups in good health, the risk of hospitalisation with Covid massively outweighs even a one-in-100,000 risk with the vaccine. The risk of hospitalisation with Covid ranges from one in 2,212 for a 55 year old woman to one in 5,587 for a 20 year old woman, for example.
Only when it comes to the risk of death from Covid do the odds start to narrow. At age 30, the risk of death from Covid during a surge in cases is one in 250,000 for an otherwise healthy woman – less than half the estimated clot risk of one in 100,000 from the vaccine.
Prof Van Tam said the decision to offer those under 30 a choice of vaccine would have a “zero or negligible” impact on the endpoint of the vaccine rollout campaign. This means all adults in the UK should still be offered a first dose of vaccine by the end of July.
For many that will still be the excellent Oxford-AstraZeneca jab – but not for all.