Immunity debt

" Immunity debt is not a new idea, though the specific coinage is fairly recent (and some experts bicker over the specifics of what the phrase does and does not mean). Its painful lesson has been learned by American honeymooners who drink the tap water in Cancún, Nigerian Americans who skip malaria prophylaxis while visiting their cousins outside Abuja, and unvaccinated seniors who were hospitalized from COVID-19 while their boosted peers suffered a mere head cold. At its heart, immunity debt is Immunology 101: Hosts whose immune systems haven’t been properly primed are more prone to infection and severe disease."

It seems there's a price to pay for all that unnecessary masking of children the last 2.5 years.

https://slate.com/technology/2022/12/immunity-debt-explainer-rsv-covid-masking.html