When I saw this, I was like

"there is a legitimate concern, but it's not the one LW's husband is raising -

if the 8 month old baby is too young to have been vaccinated,

and LW is socialising with friends who have unvaccinated kids who are in daycare/kindergarten/school and/or is in an area with less than 85% of kids vaccinated

then measles/whooping cough etc is a legit concern"

but that would be covered by only socialising with parents whose kids were all vaccinated