At some point, you've probably heard the expression that there is "safety in numbers". It turns out that whoever came up with that was right not only on a macro scale, but also on a micro scale. Today, we're going to dig in to how, when humans band together, we are able to largely eliminate infectious diseases from our communities. With the wonderful phenomenon of herd immunity, it's all for one, and one for all! Thanks to my Dad for the request for a post on this topic, as a follow-up to the recent article I posted about vaccination.
The basic concept of herd immunity is simple. You can visualize it like one of the "Colour Run" events that have been popular in the last few years. The participants get bags of coloured powder, which will be thrown up in the air and at each other until everybody looks like a unicorn. In these giant events, surely there are often some people about who didn't get their own bags of coloured powder. But they don't have to worry about staying confined to a world of shades – since everybody else has colour bombs, the people who didn't get their own are still sure to end up as rainbow as the others by the end of the day.
Protection by vaccination works in sort of the same way. Of course, vaccines directly protect the people who receive them - just like the direct recipients of the colour bombs are bound to have some smatterings of neon by the end of the event. However, there are some people who don't have the luxury of being vaccinated. This might be because they are too sick, for instance with a cancer of the immune system, or a genetic disease that inhibits a person's ability to respond well to vaccines. It could also be simply because they are too young – newborns are not vaccinated until long after they take their first breaths. These are like the people who didn't personally receive colour bombs. Thanks to the vaccinated people who surround these unprotected humans, there can still be some level of protection against disease, rubbing off on them like colour.
So, how does this work exactly? To keep on propagating, disease-causing viruses and bacteria need a certain amount of "fertile ground", i.e. unvaccinated humans, on which to grow. Being vaccinated is sort of like interrupting the food supply to these microbes. Not only do you make yourself an unsuitable breeding ground, but you also reduce the amount of fertile soil in your "region": your home, your school, your workplace, your community. Just like animals won't stick around in an area if there aren't enough food sources for them, neither will microbes. If enough people in an area are vaccinated, making them unattractive to microbes, those diseases will start to dry up.
There is a catch to all this, though. Specifically, there is a tipping point. If vaccination levels start to drop, the result can be a return of the microbes en masse to the newly fertile ground. Across Europe, this came in the form of a measles epidemic – but this can happen anywhere, and with any vaccine-preventable disease.
Practically, this means that when you decide to, or not to, vaccinate, you're not only making a decision for yourself or your child. You're making a decision that affects everybody around you. In my mind, this is basically like choosing whether or not to drive while drunk. Imagine – if you were to drive home after a handful of tequila shots, there might be some short-term benefits for you. You would get home quickly and not have to pick up your car the next day. But, as we all know, driving drunk is a terribly irresponsible thing to do. Ultimately, you put not only yourself but also everybody around you at danger. The same is true of not vaccinating.
So until next week – I challenge you to check your vaccination status (I just did - photo proof below of my Hepatitis B booster shot!) and get your (booster) shots, for the benefit of all!