An article on the blog The Exposé makes the claim that the latest data on Covid-19 from the UK Health Security Agency (UKHSA) appears to show that Covid-19 vaccines do not prevent hospitalisation or death.
While no vaccine is 100% effective, the UKHSA is clear that the vaccines are highly effective against Covid-19 particularly when it comes to hospitalisation or death. The vaccines have also been shown to provide protection against the newer Omicron variant.
The figures in question are the Covid-19 case, hospitalisation and death totals broken down by vaccine status in the four weeks to 2 January 2022. The Exposé compares the proportion of these totals which are vaccinated and unvaccinated.
The UKHSA says this data should not be used to make claims about vaccine effectiveness “because of differences in risk, behaviour and testing in the vaccinated and unvaccinated populations.”.
Essentially, you can’t isolate the effect of vaccines using these figures, because they will be influenced by other factors that differ between vaccinated and unvaccinated people.
For example, the UKHSA says that “people who are fully vaccinated may be more health conscious and therefore more likely to get tested for COVID-19 and so more likely to be identified as a case.”
Also, the estimate used for the total number of unvaccinated people may be an overestimate (as we’ve written about a number of times before), leading to the rates in the unvaccinated population to look lower than they actually are.
The latest data shows that while the case rate is higher among vaccinated people, the hospitalisation and death rates are higher among unvaccinated people.
The total number of people being hospitalised and dying of Covid-19 is higher among the vaccinated population than the unvaccinated population. But that is mainly because the vaccinated population is so large.
The UKHSA says: “In the context of very high vaccine coverage in the population, even with a highly effective vaccine, it is expected that a large proportion of cases, hospitalisations and deaths would occur in vaccinated individuals, simply because a larger proportion of the population are vaccinated than unvaccinated and no vaccine is 100% effective.”