I think the biggest problem now is these Covid virus mutations. Whilst the UK one is widespread and all the vaccines seem to be coping with it, the challenge will come with other mutations. The South African one seems to be currently the one where the various vaccines are not giving such good results. In fact, I think they have stopped giving AstraZ in S. Africa for the time being. Also the BioNTech one didn't give such good protection on tests in Israel.
The question is, will the 'lesser protection' be enough to stop hospitalisations and tests.
At the moment we have few cases of the S African type in the UK, but long term you can't stop these viruses spreading. The scientists and the pharma companies need to be working all out researching, in order to stay one step ahead. Luckily most of the vaccines can apparently be 'tweaked' to adapt to new mutations, some easier than others.