I’ve read about people who got the first vaccine and are now refusing to get the booster and I know some of these personally.
Of course, understanding why would require study by qualified professionals and not just some unqualified blogger throwing some thoughts together.
But here is my guess:
In the US, the vaccination rates of the older age groups are higher than those of the younger age groups. And boosters are recommended for the older age groups.
Now think about what happens as we age: things start to go wrong with our bodies. For example: my blog, at times, is a boring status update of my current health problems.
Within the past 3-4 years, as I went from 59 to 63 years of age, knee problems (long standing) have gotten bad enough to make me stop running. Shoulder problems took away swimming and made me alter lifting (and to do life long physical therapy). Back: yes, I first got treated in 1977, but the problems (spondylolisthesis) got bad enough for me to get an MRI and a referral to a spine surgeon. My psoriasis has flared up from time to time and excessive caffeine intake lead to urinary tract issues (happily resolved, though COVID brought some of it back)
And, if you look at my Facebook timeline, my “problems” are sort of normal for someone my age who tries to remain active.
And now go back to older people getting spaced out vaccinations and boosters. Chances are, these shots will probably coincide with something going wrong with their bodies..it is the age.
In fact, I have a reverse coincidence: right around the time I got my omicron specific booster (September 2022) my back related glute pain started to improve quite a bit…but of course, my ongoing PT, activity modification and management and slow gradual increase in walking were probably the reason.
But oh my, the timing.
The TL;DR summary: old people get shots right around the time when something goes wrong with their bodies, and they ascribe the shot as the cause.
I think this is good old “post hoc ergo propter hoc.”