I’m not sure what you or that ill informed writer are trying to argue against, and frankly I don’t think either you or she does either.
This is not at all a mystery.
Levels of protection against specific infections fall over time without boosting (by immunization or by having, frequently mild, re-infection). The rate of fall varies greatly depending on the germ, the exact mechanism of protection for that germ, and the nature of previous infections. Three years of few with any boosting of protection from RSV, and of those born just before to after Covid having a first infection with RSV, has increased the pool of those susceptible to infection by huge amounts, in children of all ages and adults both. Large pool of susceptible individuals leads to very rapid spread.
Reasonably healthy adults and older kids who have had past infection a few years back and are susceptible to infection because protection has waned still have protection, just not enough to prevent infection. They also have fairly large lower airways. Their infections are almost always mild or even asymptomatic. But they spread it and almost of the pool of those under three who have not yet had a first infection are almost all getting exposed. They have not had past infections. They have small airways. Many more of them get more sick some seriously so.
No new science required. And blaming past Covid infections for this large number of young children getting significantly ill while older children and healthy adults continue to get mostly just cold symptoms and mild cough, is beyond idiotic.
@Darren_Garrison, yes RSV has always been a significant problem. This is just the fact that pretty much everyone under three is being exposed to a first infection this year, while usually the dynamics spread out that first exposure over four or five years, including more getting that first infection at a point when their airways are larger, a big deal when the disease causes inflammation of the lower small airways (the bronchioles, hence RSV bronchiolitis). Of those who get RSV bronchiolitis about a third will also get inflammation and bronchospasm in response to many other viruses during preschool years. Some have thought that infection predisposes to such but most believe that it is more selection bias.
Yes.
Oh doubling back!
I certainly encourage patients to be fully immunized against Covid. That said, yes many kids were exposed to Covid for the first time last winter with the more transmissible variant, and as a result hospitalizations went up from very very few to very few. To put it into perspective - my six doc site had I think a total of two patients admitted with Covid over the whole pandemic; none in the ICU. Yesterday I saw four kids (all under three) in follow up from ICU admissions, three who had had RSV and one with the first Influenza B I know of in our area. It is certainly not impossible for a future variant to have greater morbidity even after past infection. Even if not, infrequent serious illness is worth preventing with the current very safe vaccination.