https://ec.europa.eu/research-and-in...vaccine-safety
Read that it covers mRNA technology simply and to the point.
Best you don't take any medications if you are worried about long term effects. All medications have side effects, hence why very few are compatible with aviation and driving in general. The Covid Vaccines actually have very mild side effects except for the extremely rare conditions that just about every medicine can invoke in some way. The nature of a medication is it changes something inside you so that it fights the condition/symptoms better than your immune system alone. But this is done by any food you eat or drink also. Anything you consume alters things inside your body in some way. Aspirin causes allergic reaction in 1% of users and up to 30% in asthmatics, but people still use that regularly, it can cause a severe asthma reaction in some people.
But like suicide rates and small businesses failing, no one cares about these things unless they can use these statistics (poorly) in their own selfish argument against something that just needs to be done. Prior to 2020 almost no one gave a dam about the suicide rate, mental health of others and woes of small business, or whether a vaccine gave you a rash except the raging lunatic anti vaxxers.