4th shot looks like a fail.
It also might cause "T cell exhaustion", a phemonenon where T cells become less effective when they constantly see antigens in the body. This phenomenon definitely occurs in situations of cancer and HIV. Could repeated vaccination cause it, too? There's some fear of that, but no proof yet.
It is important that the T cells work well against COVID, because they are the biggest factor in preventing severe disease.
I don't want to cause T cell exhaustion just to get a small boost in efficacy against symptomatic Omicron. I'll be skipping the 4th shot for now.
https://www.hsph.harvard.edu/news/hs...th-covid-shot/