One shouldn't read too much into the 94% effectiveness. The confidence intervals are huge because the number of patients in the study is small. For example, only a single fully vaccinated patient tested positive (out of 187 positive tests) whereas 18 fully vaccinated patients tested not-positive (out of 230). Roughly speaking, the 18:1 is the 94%. (The 18 and the 1 have to be adjusted for the different sizes of the groups so it's really (18/187)/(1/230) = 22, so you (a 65+-year-old) are about 22 times more likely to be hospitalized with COVID if you aren't vaccinated than if you are. That's still not quite what the study did, since they did some regression to try to account for demographic differences between the populations (and as far as I can, I'll never be able to reproduce that regression since they don't actually say how they did it.)