I do not believe you have summarized @Giltil’s claim with complete accuracy:
Taken at face value, @Giltil is here claiming that “health authorities” had “hammered home” the message that, unlike most drugs, the COVID mRNA vaccine came with no risks.
It is, of course, possible that @Giltil merely misspoke. I am aware English is not his first language. But, if that is the case, he should clarify.