I am a high risk (immunocompromised 74- year old man) and had all of my Pfizer shots and boosters. My last booster was in fall 2002. This did not prevent me from finally getting Covid ( for the first time)in December. My case was mild and you could argue that was due to my booster. However, the original mRNA shots were sold on the basis that t they were 95% effective at preventing the original Covid strain. As variants evolved that efficacy is down to 19-43%. This kind of bait and switch is one of the reasons vaccination rates are down and so many Americans now distrust public health authorities.