According to anti-vaccine campaigners, the first official data from the British health authorities would show that people vaccinated against Covid-19 would not be protected against the Delta variant. Worse: people who have been vaccinated are even more likely to die from it, some believe they know, misinterpreting an official report from Public Health England published on June 25 and covering cases identified in England (the data does not cover all from the United Kingdom).
It is true that the data in this report can be confusing: in a table published on pages 13 and 14 and often cited out of context, one can indeed see that the number of deaths of the Delta variant is higher in people aged from over 50 who are vaccinated than in those who are not.
For some, there is no doubt: this is proof of the ineffectiveness, even the dangerousness of vaccines. The diagram below corresponds to what seems to emerge from the official British report on first reading of these figures.
But beware: our brain is misled by missing data. In this case, the reflex is to think that we are comparing an identical number of people over 50 years of age vaccinated and unvaccinated. However, this is absolutely not the case.
To see it, let’s consult the official data of the National Health Service (the British health service), and more precisely the bulletin on the progress of the vaccination campaign to June 13 – which was published on the 17th, or a dozen days before the count of deaths of the Delta variant. It clearly appears that, among English people aged over 50, the unvaccinated are a minority: they represent only 3.7% of their age group.
Therefore, any comparison in absolute value of the number of deaths among vaccinated and unvaccinated gives a distorted idea of reality, since the reference population is not equivalent. Rather, what should be looked at to avoid this bias is the mortality rate, i.e. the number of deaths from a given disease compared to an equal population (often expressed per 10,000 or per 100 000 inhabitants). The picture suddenly appears in a very different light.
By figures from Public Health England, an unvaccinated 50-year-old person is actually almost twenty times more likely to die from the Delta variant than a person who is protected by a Covid-19 vaccine. These figures are consistent with other data in the report (often overlooked by anti-vaccine campaigners): they establish (page 39) that vaccination can reduce by 80% (for one dose) and 96% (for two doses) the risk of being hospitalized for a severe form of the disease. In addition, among those under the age of 50, eight died. Two had received a first dose, six were not vaccinated.