I heard a few months ago that UK infant ICU was in a dangerous spot because babies had caught all the bugs. Someone born in March 2020 would hardly have been outside until they were 1, so would be getting their first exposure to respiratory illnesses late. Babies usually get a slow, trickling exposure. By getting exposed to so many minor illnesses at once, their immune systems overloaded and they ended up in ICU with 4 or 5 things at once.