Sigh. Covid was a serious illness. We were lucky and able to leverage science that had been in development for a long time to vaccinate against it. We have a deep understanding of many immune mechanisms, and can effectively treat people against some diseases. Vaccines are super effective (until the virus evolves and then they aren't).

This is also happening with other types of pathogens - antibiotic resistant illnesses are on the rise because we used quickly created defenses to eliminate all but the strongest versions of them. We have very few effective anti-fungal medications, and most of those are very risky.

If we were good at developing defenses for homogeneity, farmers all over the world wouldn't be fungi destroying the monocultures we depend on for modern agriculture (bananas and corn are really great examples). Estimates are that as much of 30% of global crops are lost to fungal infections; I sincerely doubt that homogeneity is the panacea you assume it is.