"No one knows how the long term will end up on the vaccine"
We have no reason to expect long term effects from the vaccine - it is a new style of vaccine, & clinical trials have been accelerated, but there is intense scrutiny & research on after effects.
Whereas, we do have evidence of long-term effects of covid, with implications it can cause heart tissue damage, causing life-long health effects.
The recurrent issue with vaccines is that, yes there is a non-zero risk from taking them, but, it's dramatically lower than the risks from the disease. Adverse reactions to the vaccine are around one in a million. Vs fully vaccinated people are around 100 times less likely to be hospitalised.
UK death rates from covid currently are about double that from endemic seasonal flu, & similarly kills overwhelmingly people over 85 years old. So if you are younger, & feel anxious about vaccines, it can seem like a risk you don't need. But that has to be based on distrust of vaccination in principle, and as very probably the single most powerful medical practice that has saved more lives than any other, you have to ask why distrust has been so widespread.
Smallpox was a horrific disease, killing 30% if those infected, disfiguring the rest, it was moderately infectious with an average of 3 infections passed on per sufferer. Yet people violently protested vaccine mandates. Vaccination was made compulsory in the UK in 1853, but opposition was so strong that once the disease was wiped out, & with voluntary rates over 90% providing herd immunity, compulsion was ended in 1889, less than 40 years later. Yes the vaccine killed some. But nothing like the disease. So what's going on?
People are willing to attribute catching a disease to luck, & even layer on a moral dimension of whether someone looked after their health. A medical intervention is a bit like pulling the lever in a trolley problem, it may be that less deaths occurred, but culpability for them shifts to the lever-puller.
But the major part has I'd say to be linked to people's intuitions & instincts about hygeine. Feelings about cleanliness, like it 'being next to godliness' greatly predate germ theory. If someone spits in their own drink, & then consumes the drink & spittle, most people will feel disgust, even though what was in their mouth only goes back in. We have an intuition about a bodily envelope, & bodily emissions that leave it become suspect. Broken skin makes us feel protective, in a way which isn't reasoned. These same instincts about hygeine make people uneasy about vaccines, I think.
And following the general trend of post hoc rationalisation, that we use reason to justify what we feel, rather than feel what we have reasoned our way to, we can understand the disgust response driven by a hygiene intuition, leads to a rationalisation process for a minority, that would rather believe all scientists and doctors are in a conspiracy to maim children, than that the risks of the vaccine are reasonable to take against the risks of the disease.
This has implications for public policy:
Increasing Vaccination: Putting Psychological Science Into Action
The psychology of uncertainty, vaccinations, and protecting the most vulnerable
Victims, vectors and villains: are those who opt out of vaccination morally responsible for the deaths of others?
The last point to make, is public trust in government competance is another crucial variable. The countries of the former Soviet Union have very low vaccination rates, and low levels of trust in public health measures. Many African countries have also seen low vaccine uptake. Trust is hard to win, and easily lost. Accountability, investigations into failures, and a whole network of scrutiny are needed to build up trust. Russia made mistakes in rushing through the Sputnik vaccine without meeting internationally recognised safety & effectiveness standards, which just made it look like he valued publicity more than those things. In Africa rumours about vaccines being used after expiry based on a real story, led to the waste of many in-date vaccines, and consequent loss of life.