Point is, clean it properly and you won't have to deal with any potential side effects of the vaccine

Actually you need something like horse poop to be in the soil to contract it. It's not simply there otherwise. In WW1 it was a problem because of all the horses and not ready access to sanitation. However with the invention of the horseless carriage and CVS' and corporate farming the need simply isn't that great.

He's being a bit hyperbolic, but his point is if you clean it properly, especially if you aren't around barn animals, you'll be fine.