I mostly got the Pfizer shot. My last booster was a Moderna shot. I had a much more (good) rigorous reaction with Moderna than Pfizer.
I've had Covid-19 once, in June, 2023, less than a month after I got the first Pfizer Coivd-19 booster. I believe it was Omicron variant, for which the booster had not been updated, yet.
I certainly was not nearly as direly ill as those who caught Covid-19 in March, 2020, including some of my wife's relatives. I don't know whether that was due my own immune system, the Pfizer shot and Pfizer booster, a less virulent Omicron variant, or a combination thereof.
The Covid-19 shot is not a vaccine to prevent illness; it's more of a booster to reduce severity of illness.
The Covid-19 shot improves my odds of having a less severe infection.
Since the roll-out of the shots, Emergency Rooms and ICU's are not as overwhelmed. This could be attributed to multiple things - the MRNA shots, less virulent strains, and herd immunity.
Horseshoe bats are reservoirs of many beta corona viruses. Infected Horseshoe bats are mostly non-symptomatic, but there are many, frequent virus recombinations that lead to new strains of beta corona viruses and potentially new novel viruses.
For public officials, the decision was roll-out the shots with unknown risks, or risk global economic, social, and political collapse.
A little something is still more than a whole lot of nothing.
The spread of Covid-19 was a failure of the Chinese Communist Party, the WHO, and the CDC.