Assessing the benefits and risks of vaccinations in young people
Since the rollout of the COVID-19 vaccination campaign, it has been vital to monitor the impact of vaccinations on mortality. As with any vaccine, this includes assessing the protection the vaccine offers against infection and severe outcomes, but also measuring the potential side effects and adverse events. The balance of risk and benefit becomes particularly important in groups where the likelihood of severe outcomes from COVID-19 is lower, as in younger people. Here, Charlotte Bermingham discusses new ONS analysis on vaccine safety in the context of young people.
Rare adverse outcomes have been previously reported in young people, in particular diagnoses of myocarditis and myopericarditis associated with mRNA vaccines, and thrombotic events associated with non mRNA vaccines. The ONS publishes counts of deaths where a cause of death relating to adverse effects of the COVID-19 vaccine has been recorded. Of the 59 such deaths registered in England and Wales up to January 2023, three were in people aged under 30. However, this number may be an undercount, because not all deaths caused by the vaccine may have been recorded as such during the death certification process. Given these reported adverse reactions and deaths related to the vaccines, in our paper and accompanying release published today, we looked at whether there was an increase in the risk of death (all cause death and cardiac related death) after vaccination.
What did we look at?
Our analysis looked at the rate of deaths in the 12 weeks after a vaccination, for each dose, and compared it to the longer-term incidence of deaths. If there is a difference in the risk of death after vaccination compared to longer term, this indicates a link to vaccination. We use a method known as self-controlled case study to look at the risk of adverse outcomes following COVID-19 vaccination in young people.
What do our findings show?
Reassuringly, we find no increase in risk of death or cardiac death for young people aged 12-29 in general after vaccination. However, for females we find some evidence of an increase in the risk of cardiac death after first dose of a vaccination with a non mRNA or unknown vaccine (as opposed to an mRNA vaccine). This risk corresponds to 6 cardiac-related deaths caused by the vaccine per 100,000 females vaccinated with at least a first dose of non-mRNA vaccine.
Following safety concerns, the ChAdOx1 Oxford Astra-Zeneca vaccine was withdrawn for people aged under 30 on 7 April 2021. At that time vaccination for young people was only for those who were prioritised, therefore the young people who received a non mRNA vaccine were more likely to be clinically vulnerable and risks for this group may differ from the population in general. No increase in cardiac or all-cause death after vaccination was observed for young men for either vaccine type.
We also investigated the risk of death following a positive test for COVID-19 and, as would be expected, found it to be associated with increased cardiac and all-cause mortality among young people who were vaccinated or unvaccinated at time of testing.
Why is this important?
Whilst vaccination carries some risks, these need to be assessed in light of its benefits. In our recent publication on vaccine effectiveness we show that vaccination is associated with a reduction in the risk of COVID-19 hospitalisation and death in young people aged 16-29, despite the lower likelihood of these outcomes occurring in this age group. The vaccine effectiveness of the first booster vaccination for individuals aged 16-29 was found to be 71.0 % against COVID-19 mortality.
These studies together, alongside the many studies published on this topic, help build an overall picture of the impact of vaccinations. It is important to consider both the benefits and risks alongside each other to inform future policy on vaccinations.