Professor Philip Nolan:

There is a very simple answer to that question, which is that if the entire population was vaccinated we would still see some cases and all of those cases would be in vaccinated people. At very high levels of vaccination, it is not surprising to find that about half of the cases are in vaccinated people. What that tells us is that we are only seeing the tip of an infection iceberg, that for every infection you see in a vaccinated person the vaccines are preventing seven, eight or nine infections in other people. The unfortunate thing about that statistic is what you are not seeing is the infections that have been prevented in the vaccinated people, but you are seeing the modest number of breakthrough infections in the vaccinated people and in a similar number of infections in unvaccinated people. Further, when you look at the numbers admitted to intensive care or, sadly, the numbers dying, they remain quite radically different. The significance of an infection in a highly vaccinated population is different because that infection is significantly less likely to progress to severe disease and very much less likely to result in a death, particularly in the healthier and younger part of the vaccinated population. In no way should that statistic erode confidence in the vaccination programme. We should constantly be reminding ourselves of the huge numbers of infections that vaccination is preventing and the huge numbers of hospitalisations and deaths that vaccination is preventing in those people who are vaccinated.