這是我正在看的文章； 還沒具體看明白。
Why Mr Berenson was wrong
It is possible that the vaccine protection against symptomatic illness may wane first among older people, who were also the first to be vaccinated.
However, as we explained in detail in our previous article, there are essentially two reasons why this data cannot be used to compare outcomes between vaccinated and unvaccinated people.
The first is that we don’t know how many unvaccinated people there are. For this, we would need to know the actual populations of each age group in England, and then subtract the vaccinated people from them.
And with vaccination rates often around 90% or higher in older age groups, the population numbers have to be very accurate, or they can skew the infection rates substantially.
In its surveillance reports, PHE (and now the UK Health Security Agency, UKHSA) uses population estimates from the National Immunisation Management System (NIMS), which are higher for the older age groups than population estimates from the Office for National Statistics. This may make Covid case rates look much lower among unvaccinated people than they really are.
The second problem is that vaccinated and unvaccinated people might also differ in other ways which could affect their chance of catching Covid. For instance, vaccinated people might feel they are less likely to catch Covid, and therefore take more risks of being exposed to it.
If so, this could make vaccinated people more “likely” to catch Covid, even though the vaccine itself is substantially protecting them.
