The immunity debt theory is bullshit. At least a part of what's happening is that everyone just got exposed at the same time, rather than having infections spread out a bit more over the year. Avoiding a cold for a couple years isn't going to turn our immune systems off and erase all our immune memory, ffs. It's nonsense peddled by the same people who think constant reinfections with covid will turn it into a harmless cold.

Viruses like RSV are more severe in infants, so you would want to protect them from the virus until they are older anyway. In normal healthy children RSV presents like a typical cold. That is unless their immune function was negatively affected by something, like say, a highly pathogenic virus circulating like wildfire in schools that hurts the immune system.