My sob had rsv at 3 months and he had to be hospitalized. can he get that virus again at a later age?

Will recur : Rsv is a bothersome virus that can recur to some degree every season. It infests the surface layer of airways & doesn't enter the blood. That prevents a good immune response from forming. It tends to be a little less intense every cycle, eventually becoming a cold.Your older kid will get it again but it should not be as much trouble. Asthmatics can have significant trouble with this for many years.