The real-world study includes data on positive Covid PCR test results between May and July 2021 among more than a million people who had received two doses of Pfizer or AstraZeneca vaccine.
Protection after two shots of Pfizer decreased from 88% at one month to 74% at five to six months.
For AstraZeneca, the fall was from 77% to 67% at four to five months.
“We could be digging ourselves into a hole, for a very long time, where we think we can only keep Covid away by boosting every year,” Prof Eleanor Riley, an immunologist from the University of Edinburgh, told me.
Prof Adam Finn, a government vaccine adviser, said over-vaccinating people, when other parts of the world had none, was “a bit insane, it’s not just inequitable, it’s stupid”.
Launching a programme of Covid-19 immunisations for children should be considered only in special circumstances, leading health experts have warned.
They say UK medical authorities, who are currently studying how vaccines for adolescents might be administered, should move with great care over the implementation of such a programme.