AstraZeneca’s coronavirus vaccine may not be suitable for young people if its link to blood clots is proven to be true, one of No. 10’s top scientific advisers suggested on Monday.
‘Professor Lockdown’ Neil Ferguson said older and middle-aged groups should ‘very much’ get the vaccine because the threat of coronavirus far outweighs the risk of the clots, thought to affect just one in 600,000 people given the jab (0.00017 per cent).
But the SAGE epidemiologist, 53, who himself has had AstraZeneca’s jab, said the balance of risk is ‘slightly more complicated’ when younger people who are less vulnerable to the virus are considered.
The risk of blood clots from the vaccine may prove to be higher in younger age groups.
British scientists say the risk of dying of COVID for 25 to 44-year-olds is 0.04 per cent, and 0.01 per cent for people aged 15 to 24. For comparison, the rate is up to 6 per cent in elderly age groups.
It comes after several European countries – including Germany, Spain and Norway – suspended the British-made vaccine after dozens of vaccinated people suffered a rare brain clot, known as CVST, or cerebral venous sinus thrombosis.
The UK’s medical regulator has seen 30 similar cases, of which seven people have died. But it insists its analysis has still not found any evidence the vaccine is causing the clots, a finding which has also been echoed by the EU’s medical watchdog.
Professor Ferguson told the BBC Radio 4 Today Programme: “In terms of the data at the moment, there is increasing evidence that there is a rare risk associated, particularly with the AstraZeneca vaccine.
“But it may be associated at a lower level with other vaccines, of these unusual blood clots with low platelet counts. It appears that risk is age-related, it may possibly be – but the data is weaker on this – related to sex.
“And so the older you are, the less the risk is and also the higher the risk is of COVID so the risk-benefit equation really points very much towards being vaccinated.
“I think it becomes slightly more complicated when you get to younger age groups where the risk-benefit equation is more complicated.”
Because health experts aren’t sure how common CVST normally is in the wider population, they are still uncertain if it is occurring more in vaccinated people than it otherwise would.
CVST, or cerebral venous sinus thrombosis, is a blockage in a vein that carries blood away from the brain and it can lead to strokes or bleeding inside the skull.
Scientists say it’s morally complicated to jab children because they have almost zero risk of dying or falling seriously ill from the disease, and would only be vaccinated to protect older people. It is still unknown, however, how long COVID may affect them.
The risk of dying from COVID-19 is significantly higher than the rate of CSVT blood clots, which haven’t even been definitively linked to the vaccines (Based on fatality estimates from Cambridge University and CSVT occurrences in Germany)
At least 10 countries in Europe, joined by Germany last night, have put some kind of restriction on the use of AstraZeneca’s jab, mostly opting to give it only to over-60s because the CSVT cases seem to be happening in younger adults
The UK’s MHRA regulator announced on Friday it has seen 30 brain clot cases in 18.1million AstraZeneca-vaccinated people – around one in every 600,000 people (0.00017 per cent).
The UK’s health watchdog said it hadn’t seen CVST cases in people who got the Pfizer jab but there was still no proof the AstraZeneca vaccine is raising the risk. This may be because different groups of people are getting different vaccines.
Germany last month went against the European regulator’s advice and banned the AstraZeneca jab for under-60s because it fears a link to the condition.
Scientists say the balance of risk is ‘very straightforward’ and clearly in favour of vaccination because of the ‘extreme rarity’ of CVST cases.
The main benefit of giving the COVID-19 vaccine to younger people is that it protects elderly members of society, whose risk of death is much higher, and therefore allows ministers to loosen lockdown rules.
Professor Adam Finn, a University of Bristol researcher and government adviser on vaccines, said: “The extreme rarity of these events in the context of the many millions of vaccine doses that have been administered means that the risk-benefit decision facing people who are invited to receive COVID vaccines is very straight forward: receiving the vaccine is by far the safest choice in terms of minimising individual risk of serious illness or death.’
Comparing the rates of CVST to coronavirus death is tricky for a number of reasons, including that it’s so rare data aren’t clear, and that more people will get a jab than catch coronavirus.
Regulators also don’t break down the CVST cases by age, although they are thought to be more common among young adult women.
And the fatality rates for coronavirus, estimated by Cambridge University experts only include people who get the virus.
This means the average person’s actual risk of dying from coronavirus is significantly lower than the estimate because not everyone catches it – although if nobody took the vaccine, the likelihood of them catching it one day is far higher.
Johns Hopkins University in Baltimore, US, estimates that one in every 200,000 people of all ages develop CVST each year.
The European Medicines Agency said last week, echoing data from Germany, that the risk appears to be one in 100,000 in under-60s who have had the AstraZeneca vaccine.
But much of the data comes from Germany’s AstraZeneca vaccine patients, who are mostly young female adults, and young female adults are statistically more likely to get CSVT even when there is no vaccine around.
EMA director Emer Cooke said cases in women usually outnumber those in men by 10 to one.
In the wake of EU scare stories over the AstraZeneca jab, which came amid a row over supplies, the MHRA last month said there had only been five cases of CVST among 11million administered doses.
In last week’s update, which took into account all adverse reactions recorded up until March 24, it put the count at 22.