Are pesticides and GMO foods - two things which are reapplied on a frequent basis, relatively speaking - actually comparable to an instance in time where someone received one or two shots once? I think the most famous/deadly instances of drugs having side effects which discovered after mass deployment have generally been for medicines one ingests continuously, no?

I, as an untrained and uneducated individual, find it almost impossible to imagine a drug / technology / mechanism which could be applied "once" (i.e. only one time, even if over a few doses spaced out in time) that would not present any population effects after 1y / 1billion people that would then proceed to be even within one order of magnitude as deadly as COVID. Hell, two or three even...