It's as obvious as the nose on one's face that sanitation and nutrition are the biggest factors on reducing disease.
Firstly, thanks for posting a chart. Most of the times I disagree with someone on here, the other person just posts a link to someone on youtube ranting in his basement as "evidence". This makes a refreshing change!
Secondly, I'm not disputing that sanitation in particular is vital, of course it is, particularly with typhoid. In more deprived countries, better sanitation and access to clean water would lead to a profound reduction in many afflictions - such as schistosomiasis, which is a huge problem (affecting 240 million people globally, and causing an estimated 200,000 deaths a year...
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But just because one thing is effective, it doesn't mean it's the reason for everything. Let's consider typhoid - and scarlet fever, which you also mention - antibiotics have been hugely important in reducing case numbers for both of these. It's not merely sanitation. Similarly, vaccines are a vitally important weapon in the medical arsenal. If Covid is transmitted primarily through inhalation of respiratory droplets, then everyone washing their hands isn't going to stop the pandemic... whereas vaccines, as the data show, are.