The risk of dying from heart issues was three and a half times higher among young women in the first three months after a single dose of the AstraZeneca Covid vaccine, according to a new study.
The Office for National Statistics (ONS) analysed hospitalisations, vaccination records and death registrations in England among 12 to 29 year-olds to assess the impact of the Covid-19 jab and infection.
After one dose of a non-mRNA vaccine, which includes the AstraZeneca jab, there was evidence of an increased risk of cardiac death in young women, the ONS said.
Cardiac death could include cardiac arrest, heart disease, and myocarditis (inflammation of the heart muscle).
The risk was 3.5 times higher in the 12 weeks following the vaccination, compared with the longer-term risk.
If there is a difference in the risk of death after vaccination compared to longer term, this shows a link to the jab, the researchers said.
However, overall among 12 to 29 year-olds in England mortality was not significantly increased in the first 12 weeks after a vaccination, compared to the longer-term risk.
The number of deaths registered in England involving Covid-19 vaccines causing adverse effects is miniscule compared to the number administered - 59 compared with 144.7 million.
Of the 59 deaths, three were in people aged under 30, the ONS said.
Six cardiac-related deaths
The 3.5-times greater risk among young women following the AstraZeneca jab corresponds to six cardiac-related deaths per 100,000 vaccinated with at least a first dose, according to the study, which was published in the journal Nature Communications.
The data relate to vaccinations given between December 2020 and June 2022.
Most of the young people who received the AstraZeneca jab before April 2021 would have been prioritised due to underlying health conditions, or because they were healthcare workers.
Therefore, the 3.5 times greater risk cannot be generalised to the whole population, the ONS said.
There was no strong evidence of an increased risk of cardiac death after vaccination for young men for either vaccine type, non-mRNA (AstraZeneca) or mRNA (Pfizer and Moderna).
In April 2021, the Medicines and Healthcare products Regulatory Agency (MHRA) confirmed a link between the AstraZeneca jab and rare blood clots.
In response, officials recommended that under 30s receive an alternative vaccination because the balance of risk versus benefit of the jab was more “finely balanced”.
Since then, further research has linked the Covid vaccination with an increased risk of heart diseases and rare blood clots.
Myocarditis has been identified in rare cases following the Pfizer and Moderna jabs in the UK, and are more common in young males.
The ONS also examined the increased risk of death after testing positive for Covid, and found it was raised for both cardiac and all-cause deaths among people.
The risk was higher in those who were unvaccinated, they added.
Analysing hospital deaths of those who tested positive for Covid, the researchers found 13 per cent were unvaccinated, compared to three per cent who were vaccinated.
Vahé Nafilyan, senior statistician at the ONS, said: “We find no evidence that the risk of cardiac or all cause death is increased in the weeks following vaccination with mRNA vaccines.
“However, receiving a first dose of a non-mRNA vaccine was associated with an increased risk of cardiac death in young women.
“Vaccination with the main non-mRNA vaccine used in the UK was stopped for young people following safety concerns in April 2021, and most of the young people who received it would have been prioritised due to clinical vulnerability or being healthcare workers. Therefore, these results cannot be generalised to the population as a whole.
“Whilst vaccination carries some risks, these need to be assessed in light of its benefits. Our analysis shows that the risk of death is greatly increased following a positive test for Covid-19 even in young people and many studies show that vaccines are highly effective at preventing hospitalisation or death following Covid-19 infection.
"We will continue to monitor data on vaccinations as further doses are rolled out and produce analyses such as this study that contribute to the body of knowledge on risks and benefits of vaccination."
Prof Adam Finn, professor of paediatrics at the University of Bristol, said: “These are interesting data which generate as many questions as answers. The findings are somewhat unexpected, as concerns about rare cardiac side-effects – specifically myocarditis and pericarditis – have hitherto been particularly associated with mRNA vaccine second doses in males especially when the dose interval was short, whereas the signal reported here is primarily in non-mRNA first doses in females.”
He added that more details were needed about the nature of the reported cardiac events, to help understand the figures and “guide future policy and vaccine design”.