People under the age of 40 are to be offered an alternative to the AstraZeneca vaccine as evidence grows that younger people are more likely to be affected by rare blood clots linked to the jab, The Independent can reveal.
The policy currently applies to the under-30s, but the Joint Committee on Vaccination and Immunisation (JCVI) has recommended that the age threshold be raised after Britain’s medicines regulator reported new figures on clots last week.
A senior government source insisted that the change would not impact the UK’s target of offering a first vaccine dose to every adult by the end of July, because of the availability of supplies provided by Pfizer and Moderna.
The source said that the precautionary decision to offer an alternative jab to the under-40s was also driven by the “flexibility” of the vaccination rollout and Britain’s falling Covid-19 infection rates, which mean that, on balance, the risk posed by the blood clots is now greater in younger age groups.
According to the latest weekly figures from the Medicines and Healthcare products Regulatory Agency (MHRA), the case incidence of the rare brain clots combined with low platelet counts is 10.5 per million doses.
“Because prevalence of Covid is low, and given the strength of the programme, that means we’re in a position to act with an abundance of caution and offer a different vaccine to the younger groups,” the source said.
A statement was drafted earlier in the week by the JCVI – which provides recommendations, but not policy, to the government – and an announcement is set to be made on Friday. No new safety concerns surrounding the vaccine have been raised.
The latest data from the MHRA shows that, up to 28 April, there had been 242 cases of the rare clotting disorder following vaccination using the AstraZeneca jab, with more than 28 million doses administered to date.
Some 24 cases were reported in people aged 18 to 29, 31 in those in their thirties, 38 in people in their forties, 68 in people in their fifties and 67 in those aged 60 and above, with the age not known in the remaining cases.
More than a fifth of the rare blood clots were in people aged under 40, and two-thirds in those under 60, the data shows.
This contrasts with the proportion of people in different age groups who have been vaccinated. By 25 April, 5.5 million people under 45 had received a first dose, compared with 22.6 million of those 45 and over, pointing to a higher incidence rate in the young.
For people in their twenties, the risk of hospitalisation with Covid-19 is similar to the risk of harm posed by the vaccine - a factor that drove the JCVI to introduce the initial policy. A similar balance of risk is now being reached for those over 30 due to the UK’s falling infection rates, though this age group is still more likely to fall seriously ill from the virus.
The MHRA has said that no medicine or vaccine was without risk but insisted that the blood clots were “extremely rare”.
“The benefits of the vaccine continue to outweigh the risks for most people,” said the regulator’s chief executive, Dr June Raine.
“It is still vitally important that people come forward for their vaccination when invited to do so.
Pregnant women have already been told that they should receive an alternative to the AstraZeneca vaccine, but GPs have warned that the NHS is struggling to enforce this policy.
Official guidelines say these patients should preferably be offered the Pfizer or Moderna vaccines, but the NHS National Booking Service says it does not have any information on how these can be accessed and directs women to their family doctor. Doctors’ leaders have called for changes to the system.
Blood experts have meanwhile said that the rare clotting syndrome seems to be largely triggered in people who have received a first dose of the AstraZeneca vaccine, rather than a second.
“That certainly appears to be the case,” said Dr Sue Pavord, a consultant haematologist at Oxford University Hospitals. “In theory, it might be much less likely because if this profound immune reaction didn’t happen after the first dose … then they're not going to get it after the second dose.
“But obviously, fewer people have had a second vaccination and it is a rare condition, so we are always looking out.”
Dr Pavord said there was a median age of 49 among the cases that her team had treated so far.
“It appears to affect males and females equally and all ages, but the fact we're seeing it in young cases where less young people have been vaccinated, that incidence is really important to understand,” she said during a Royal Society of Medicine webinar on Thursday.
“That's why I think the MHRA are really keeping an eye on the cases. They are looking at age-based incidents of this condition compared with numbers vaccinated, and comparing that with statistical modelling of Covid-19 infection and fatalities per age group.”
For those hospitalised with the condition, doctors have begun to treat patients with intravenous immunoglobulin (or antibody) therapy. This helps to raise the individual’s low platelet count “pretty successfully and appears to stop or slow the autoimmune process”, said Dr Pavord.
A Department of Health and Social Care spokesperson said that the position of the MHRA and the JCVI “continues to be that the benefits of the Oxford/AstraZeneca vaccine outweigh the risks for the vast majority of adults”.
“We hit our target to offer a vaccine to everyone in phase one of the vaccination programme and we are on track to offer a jab to all adults by the end of July,” they added. “The JCVI keep their recommendations under review in line with the latest scientific advice.”
Across Britain, 34.9 million people have received a first vaccine dose, while 16.2 million people have received both shots.