Originally Posted by
garykung
None of these works for OP.
Apparently, OP intends to visit the newborn. The newborn obviously has no passport (yet). What's the point?
The idea is that the OP grandparent would spend fifteen days (be careful about how the USA defines fourteen days) in Mexico etc. and then travel to the USA to see the grandkid. A test would be required while in Mexico for departure to the USA. Parents and new kid never leave the USA in this scenario.
Personally, I'd worry about this unless the mother has been vaccinated as babies seem to get protection from their mothers.