Well domesticating animals was a huge part of it, and so is switching your diet. Google "zoonotic illness." Almost every plague known to mankind started from eating animals or direct contact with domesticated animals. Unsanitary conditions on crowded factory farms just increases this possibility.
COVID-19 came from eating wildlife. HIV came from humans eating other primates. When are people gonna learn. Even if you don't GAF about "animal rights" eating plants is the way to go for your own health, and the future of civilization. Animal agriculture and deforestation are two big contributors to both manmade climate change and pandemics like the one we are living through.
In case this came across as too scientific and not spiritual enough, I'd like to point out that vegetarianism and respect for life is a huge tenet of several major world religions, including some groups of Buddhists, like this one: http://www.cttbusa.org/vegetarianism/cttbveg.asp