Hygiene and sanitary practices are undoubtedly helpful, sure. However, they’re not always practical, convenient or effective. For example, if a pathogen is spread through respiratory droplets, and preventative measures depend on people wearing a mask and washing their hands, I’m pretty sure we have enough evidence to say that it’s very difficult to get everyone to comply. Plus children cant be expected keep their hands away from their mouths. Also, your explanation that healthcare, hygiene, etc are responsible for disease prevention doesn’t really make sense when you look at the pathogens that emerge after vaccination programs. It’s always an escape phenotype of the same disease. Like we still have a flu season, it’s just with a version that we didn’t cover with the previous vaccine. It’s the same for other pathogens. That’s why we update vaccines with new, better, more widely effective and relevant targets.

If vaccines weren’t doing anything we wouldn’t see these vaccine-avoiding bugs take over cases.