Regrettably, the data which support the assertion of a faster decline of booster effectiveness vs hospitalisation in the 75 and older age group is unpublished. “We know that, after each dose of a Covid vaccine (at least up to dose 4, and probably further doses) the immune response is enhanced in several ways. “Unless the immune system is triggered by exposure (to virus or vaccine), antibody levels gradually fall away. It also helps to broaden the immune response, so that the cellular immune response will better recognise closely related viruses (such as variants). Dr English sometimes receives honoraria for acting as a consultant to various vaccine manufacturers, most recently to Seqirus.”None others received.

Source: The Guardian February 21, 2022 16:18 UTC