SARS-CoV-2 variants of concern and variants under investigation in England
Technical briefing 17
25 June 2021
Professor Norman Fenton’s comments from his twitter account
Some people are looking at today’s Public Health England report and concluding the Case Fatality Rate for Delta positive cases is 6.5 times higher for vaccinated compared to unvaccinated. But this is an instance of Simpson’s paradox as shown by this table
In both age categories the rate among vaccinated is lower but when aggregated vaccinated is higher. It’s because a much greater proportion in the older group are vaccinated compared younger group & most deaths occur in the former.
It’s worth noting, however, that in the <50 age group there’s little difference in fatality rate between vaccinated & unvaccinated.
Also important to note that the data that is completely missing is that relating to deaths (or serious adverse reactions) of vaccinated v unvaccinated people who were NOT classified as having COVID. So no information on vaccine risks.