Originally Posted by Gazza-d

Israel lead the world in vaccinating so have had the longest period and are seeing immunity wane. We have not seen it in the UK but were a couple of months behind Israel. Also a big difference is that Israel and many other countries including the US only had 3 weeks between shots, the UK apart from the early shots had a much longer gap, 10-12 weeks. This larger gap seems to have imparted a much stronger response. So a top-up may or may not be necessary. The initial talk was that any booster would be tweaked to better fight the variants but that seems to have been dropped in favour of a general strengthening of immunity. There is also the school of thought that once vaccinated any introduction of covid to the system would in itself act as a booster. I guess time will tell.