Simultaneously, air pollution is down, which lowers symptoms.
So it wouldn't surprise me if respiratory incidence is down. Of course there were also more kids in the 1970s, to your point.
That’s very likely true.
> one big difference is indoor air ventilation standards improved dramatically, leading to less spread of disease indoors.
I don’t know if this is. In 1975 air conditioning was much less prevalent, so people were much more likely to open windows. Buildings were also much leakier.
And it’s not simple as building ventilation has steadily improved, so teasing out the impact is almost impossible. In the 80s there was a big push for energy efficiency, so we went from 15 cfm/person in 1973 to 5 in 1981 then back to 20 in 1989.
But building envelopes also got much tighter, so there’s less uncontrolled ventilation.
I think respiratory flu is far less common now than it was. I have had a legit case of the flu only once in my adult life. After spending 15 years teaching in a public school, I had countless colds but never caught the flu. Of course, annual flu vaccines might have helped. Those weren't available in the 70s.
Strep throat was also a very common complaint in the letters. Throat cultures, home visits from the pediatrician, etc., were frequent, especially for my brother. I haven't seen a single case of strep in my extended family since. Maybe just lucky.
Many things have improved over the decades, but we do have an array of exciting tick-borne illnesses to make up for it!
They’re not far less common in average. Rates have gone down a bit with the annual flu shot, but there’s a few things going on.
-Flu rates vary wildly by year and decade. There were a few big pandemics where a very large percentage of people got the flu.
-There was no way to easily test for the flu, so people said they had it more frequently than they did.
In a given year about 12% of kids will come down with symptomatic influence which is not too far off from what we can estimate that historic numbers were in an average year.
>Strep
I looked up studies on this. Nothing conclusive, but likely no large change.
Recommendations about when to test have changed though because it turns out that if you culture every kid with a runny nose a large percentage of them will come back positive even though their symptoms are viral.
So you’re probably right that you notice fewer diagnosed strep cases, but there aren’t actually fewer symptomatic cases.