Why vaccinated people can still die of Covid-19

By Stuff reporter

The Whole Truth: Covid-19 Vaccination | Report from Stuff

Yes, some vaccinated people will still get sick and even die. But that doesn’t mean the vaccine doesn’t work.

We know the Pfizer vaccine is highly effective against Covid-19, preventing severe disease in about nine out of ten people, even for the Delta variant.

But no vaccine works 100 per cent of the time.

That means some vaccinated people will still get infected with Covid-19. These are known as breakthrough infections. While vaccination reduces the amount of virus and the likelihood of serious disease, some of those infected will still get sick and could even die. 

Data from Britain show much lower case numbers among those who have had two Covid-19 jabs.

Of the country’s 56,098 cases of the Delta variant recorded from June 14-21, just 6747 (12 per cent) were fully vaccinated people. That’s despite 46 per cent of Brits being fully vaccinated by then.

As of June 21, 36 per cent of the population had received no vaccinations. However, with 36,411 infections, that group made up 65 per cent of all recorded Delta cases.

But at first glance, the death statistics are confusing. 

Of the 255 people who died within 28 days of testing positive for Delta, 118 (46 per cent) of them were fully vaccinated. That’s higher than the 92 deaths (36 per cent) in unvaccinated people.

So how does that work? Basically, it’s a numbers game — as the proportion of vaccinated people increases, you eventually hit a point where more vaccinated people are affected than unvaccinated people.

That’s because a small percentage of a big number can still be larger than a big percentage of a small number.

Take this example of a measles outbreak in a school of 1000 pupils, where 950 children (95 per cent) are vaccinated and 50 children are not.

The measles vaccine is about 95 per cent effective at preventing measles, so about 48 vaccinated kids (5 per cent) would still get the disease. And because measles is so infectious, almost all the 50 unvaccinated kids would also be infected. 

The British Covid-19 deaths conundrum is a bit more complicated, because the vast majority of those who died (229 out of 255) were aged over 50. 

That’s important for two reasons. One, because older people are at much higher risk of dying from Covid. Some deaths in the elderly are also likely to be frail people dying with Covid, rather than from it.

And two, because — like New Zealand — Britain has prioritised older people in its vaccine roll-out. That means that age group has much higher vaccination rates.

The British data doesn’t give date of death, so you can’t pinpoint the size of the vaccinated population when each death occurred.

But as a rough guide, by May 31, 16.8 million over-50s had received two jabs, whereas only about 1 million remained completely unvaccinated. So 116 deaths in fully vaccinated over-50s is a death rate of about 7 deaths per million. Whereas 71 deaths in unvaccinated over-50s represents a death rate of about 67 per million. 

So while the bare numbers might make you think the vaccine doesn’t work, in reality unvaccinated people are dying at almost 10 times the rate of those who have had both jabs. 

In fact, Public Health England estimates that vaccination prevented more than 30,000 deaths in England up to 25 June 2021.

Reporting disclosure statement: Otago University professor Peter McIntyre provided expert advice for this post. It was also reviewed by The Whole Truth: Covid-19 Vaccination expert panel member Dr Maia Brewerton.