We've researched coronaviruses since the 1960s, had MERS and SARS most recently (less recent the 2018). I don't understand why we worry about long term effects

We've researched coronaviruses since the 1960s, had MERS and SARS most recently (less recent the 2018). I don't understand why we worry about long term effects of Covid, but not long term effects of mRNA vaccines? Both seem to have things to worry about, with both having different scales. https://www.cdc.gov/coronavirus/types.html https://www.cdc.gov/coronavirus/types.html