More Vaccinated People Are Dying of COVID in England Than Unvaccinated – Here’s Why

According to a recent report from Public Health England (PHE), more vaccinated people die from COVID than unvaccinated people. The report found that 163 of the 257 people (63.4%) who died between February 1 and June 21 within 28 days of a positive COVID test had received at least one dose of the vaccine. At first glance, this may seem alarming, but it is exactly as you would expect.

Here’s a simple thought experiment: Imagine everyone is now fully vaccinated with COVID vaccines — which are excellent, but can’t save all lives. Some people who become infected with COVID will die anyway. All these people will be fully vaccinated – 100%. That doesn’t mean vaccines aren’t effective at reducing death.

The risk of dying from COVID doubles approximately every seven years that a patient is older. The 35-year difference between a 35-year-old and a 70-year-old means that the risk of death between the two patients is five times greater – equivalent to a factor of 32. An unvaccinated 70-year-old is 32 times more likely to have to die from COVID than an unvaccinated 35-year-old. This dramatic variation in the risk profile with age means that even excellent vaccines do not lower the risk of death for older people below the risk for some younger demographics.

PHE data suggest that double vaccination reduces the risk of hospitalization with the now dominant delta variant by about 96%. Even if we conservatively assume that the vaccines are no more effective at preventing death than hospitalization (in fact, they are probably more effective at preventing death), this means that the risk of death for double-vaccinated people has been reduced to less than a twentieth of that. the value for unvaccinated people with the same underlying risk profile.

COVID infections are currently highest among young people.

However, the 20-fold reduction in risk offered by the vaccine is not enough to offset the 32-fold increase in the underlying risk of death for a 70-year-old over a 35-year-old. Given the same risk of infection, we would still expect more double-vaccinated 70-year-olds to die from COVID than unvaccinated 35-year-olds. There are caveats to that simple calculation. The risk of infection is not the same for all age groups. Currently, infections are highest in the youngest and lower in the older age groups.

Think of it as hail of bullets

One way to imagine the risk is as a shower of different-sized ball bearings falling from the sky, with the ball bearings being the people who become infected with COVID. For simplicity, let’s assume that there are about the same number of ball bearings in each age group. In each age category there is also a variation in the size of the balls. The balls representing the older groups are smaller, which means a higher risk of death.

Now imagine that there is a sieve that catches a lot of the balls. Most people who get COVID don’t die (most balls get stuck in the strainer). But some of the smaller balls fall through. The older you are, the more likely you are to fall through the gaps. The balls coming through the first sieve are hugely skewed towards older age groups, represented by the smaller ball bearings. Before COVID vaccines came, the people who fell through the gaps represented the people who would die from COVID. The risk was hugely skewed toward older people.

Vaccination creates a second sieve under the first, to prevent people from dying. Because we didn’t vaccinate everyone this time, it’s the holes in the sieve that are of different sizes. For older people who have had both doses, the holes are smaller, so many ball bearings have stopped. The vaccines will save many who would have died earlier.

For younger people, the holes in the vaccine strainer are currently larger because they are less likely to receive both doses and are thus more likely to fall through the strain.

If all the filtering had been done through the second sieve alone (without the risk of death by age represented by the first sieve), we might expect younger unvaccinated people to account for a higher proportion of deaths. But that’s not it. The first sieve is so strongly biased against older people that even with vaccination, more of them slip through the second sieve than the younger unvaccinated people. Given the UK’s vaccination strategy (vaccinating older, more vulnerable people first), you would expect that a large proportion of people who die from COVID have been vaccinated. And that’s exactly what we see in the data.

The fact that more vaccinated people die than unvaccinated people does not affect the safety or effectiveness of the vaccine. In fact, it is exactly what we would expect from the excellent vaccines, which have already saved tens of thousands of lives.

Written by Christian Yates, Senior Lecturer in Mathematical Biology, University of Bath.

Originally published on The Conversation.