Protection stemming from in utero possible?

Husband is dead against Covid shots for the kid as he call it poison, but he got the J&J way back in beginning and I’ve had multiple rounds of Moderna. One of the boosters I got while oldest kid was cooking inside me. I imagine kiddo gets the same-ish level of protection as they would when I got the flu, RSV, TDAP and all the other fun stuff you can get while pregnant. I recall my doctor saying it’s recommended I get specific shots at the 32-36 week mark to essentially extend coverage to the newborn. Kiddo is now 2.5 years old and I plan to get him the latest Covid shot because I’ve got another on the way and want to protect both the newborn and the toddler. (I already got the Flu, Covid and RSV shots at the same 32 week mark in this pregnancy as well).

Could I get some help with establishing why it’s not poison? I’m struggling with preggo brain and can’t come up with more than, “look it up yourself” because I’ve been following stuff for years at this point and kid is getting the shot - CVS in my area I believe only carries Moderna - but he keeps ranting about how it’s “poison” and no one is talking about it anymore. Ugh. Thank you in advance!