Advertisement

COVID-19: Why the risk-benefit balance of AstraZeneca jab for young people looks to have shifted

The risks posed by the Oxford-AstraZeneca vaccine to young adults in their 20s and 30s may now be outweighed by its benefits, according to the calculus used by the Joint Committee on Vaccination and Immunisation (JCVI) to decide which age groups should get which vaccine.

With Britain now in the midst of another full-blown wave of COVID-19, the risk-benefit judgement looks to have shifted, with the upshot that the benefits from the vaccines may now outweigh those risks for all age groups.

In April, the JCVI recommended that, in the light of a small number of severe side-effects and deaths among those receiving the AstraZeneca vaccine, those aged under 30 should be given the option of receiving an alternative vaccine from Pfizer or Moderna.

The subsequent month it recommended the same thing for those aged under 40.

Those decisions were taken - in part - on the basis of low COVID-19 incidence at the time, which in turn reduced the risks of the average person contracting the virus and, potentially, being admitted to intensive care.

In April, according to data provided by the Medicines and Healthcare products Regulatory Agency (MHRA) to Cambridge University's Winton Centre for Risk and Evidence Communication, the risks from side effects among 20-29 year olds (or rather the risk of a blood clot episode) averaged 1.9 per 100,000 people, compared with an average risk of COVID-related admission to intensive care of 0.2 per 100,000 people.

In other words, at that point, when roughly one in 600 people had COVID, the risks of the vaccine outweighed the benefits for those in their twenties and, narrowly, those in their thirties as well.

However, since then the number of COVID-19 cases has risen sharply, changing that calculus.

The latest Office for National Statistics (ONS) survey of incidence in England suggests that one in 75 people may currently have COVID-19.

The upshot is that the risk for a 20-29-year-old of being admitted to intensive care for COVID has risen to 2.2 in 100,000 - still a very low level, but nonetheless higher than the 1.9 per 100,000 risk of a blood clot incident.

Indeed, those new ICU risks reflect COVID levels somewhat below the latest ONS figures.

The calculus underlines the changing balance of risks facing those deciding upon vaccination, strengthening the case among all age groups.

However, there remain many unknowns on both sides, which are not reflected in this calculus.

Those unknowns include the long-term side-effects from the vaccine, as well as the long-term consequences from COVID-19.