Since the start of the coronavirus COVID-19 pandemic, the term “herd immunity” has been all over the news. But what does it really mean? One thing most people don’t realize about vaccines is that they aren’t just to protect the person who gets the shot. They also protect the population as a whole… even people who didn’t get the shot. In this video, we use lots and lots of mousetraps and ping-pong balls to show you how that works.