There was a website where you could look up how bad your jab was to see how other people fared who got your same batch of shots. It was pretty amazing the different reactions in batches from the same company.
My one shot batch had a 1.4% fatality rate, of which I came very close to being part of.
Yes, many people had serious side effects. Hopefully the percentage was small. On hindsight, I probably would have skipped the jabs. But in 2021 there was considerable panic about covid, and I decided to get the jabs. 2nd jab had quite noticeable effect, such as feeling tired and lack of energy and some body ache similar to flu coming in. If I had such reaction, while I am in top physical condition with daily gym exercise, I can easily visualize old folks with health issues could experience more severe side effects.