The biggest problem with the hypotheses masks eliminated the flu, is the fact viral interference has occurred with other pandemic viruses. All of which masks, distancing, and other draconian measures weren't instituted during other pandemics. Yet its a phenomenon that occurs during other pandemics. That assessment doesn't cut it.
Not to mention, if masks were 50% effective, you'd expect heavily masked counties to have much better epidemiological curves compared to less mask stringent counties. That simply doesn't bear out in real world data. Almost every curve is nearly identical based on similar climate areas. As for 15% efficacy of masks, article below from Reuters summarizing the data. There is also an NIH study showing negligible effect on hospitalization, resources or mortality of instituted mask mandates. Below is just one example of a graph of mask mandate, then cases skyrocketing post mandate, my claim isn't masks cause soaring cases, but they have far less effect than 50% efficacy.
Also to suggest things are a lot different on campus is false, last fall, yes the campus shut down in November, but spring term ran much like current rules which have been in place on campus currently. I see it daily working on campus having to abide by the guidelines. As for vaccines, absolutely they are having the effect keeping cases relatively low on campus. But lets be honest, the dome being full and mask scarce is essentially the same or slightly better than being crammed together partying at a house party or frat. I can assure you those occurred all spring, I saw the kids congregating or partying as I walked to my car, I can assure you, spring isn't much different than today.
Last point, the flu currently being spread is flu A which is less stable and more prone to mutation, so historically the flu shot is far less effective protecting against that strain, than flu B which is stable, and less prone to yearly mutations.
Danish study
Study of Bexar county
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