A broad sweep of a review article, just published in NEJM nejm.org/doi/full/10.1056/N...
It covers the current Covid19 vaccines, how well they neutralise new variants of the virus, how their performance wanes in time, and in terms of both humoral and cellular immune responses.
The paper questions the current strategy of booster vaccinations every 4-6 months, notes that the latest omicron-specific vaccines are not much better at neutralising omicron than the early-developed vaccines, and argues that "the most important goal of Covid-19 vaccination should be to provide long-term protection against severe disease, hospitalization, and death from current and future variants". And in its concluding remarks "It is therefore important for studies of Covid-19 vaccines and boosters to evaluate not only short-term neutralizing antibody titers but also durability of antibody responses, memory B-cell responses, and cross-reactive T-cell responses".