The 12 billion or so COVID vaccine doses given also only have a history of ~2 years. If the adverse effects of it were say for instance, minor cardiac damage that resulted in no acute symptoms, but instead an overall reduction in life expectancy by 5 years, the costs of such would not be known for some time. Another side of this is the possible cumulative effects of ongoing covid vaccination boosters that have no long term data.
Finally also the danger of immunological imprinting[1] possibly resulting in less than optimal immune response. The fact these vaccines have little impact on transmissibility means basic evolutional biology theory is at play, driving selective pressures for antigens humans are less capable of mounting defenses against thanks to an already primed imuno response of the original virus' antigens. This is evident with the proliferation of variants and sub variants.
Finally also the danger of immunological imprinting[1] possibly resulting in less than optimal immune response. The fact these vaccines have little impact on transmissibility means basic evolutional biology theory is at play, driving selective pressures for antigens humans are less capable of mounting defenses against thanks to an already primed imuno response of the original virus' antigens. This is evident with the proliferation of variants and sub variants.
[1] https://en.wikipedia.org//wiki/Original_antigenic_sin