When enough people are vaccinated against a contagious disease they will create protection for those who aren't vaccinated, in an effect known as "herd immunity".
This effect can eventually lead to the eradication of diseases and also helps those who are not able to receive vaccinations due to medical reasons, such as immunosuppressed children or those going through chemotherapy. But does it mean it's a good idea to ride on the back of the vaccinations of others? Here’s why it's important to keep vaccination rates as high as possible.
Redditor theotheredmund has created a GIF that shows how a contagious disease passes through different populations with varying percentages of its people vaccinated. The simulated data was based on research from a study published in Epidemiologic Reviews in 1993.
The 6-second animation clearly shows how populations with fewer people vaccinated allow the disease to spread significantly quicker and further through the chain of humans. On the other hand, if there is any outbreak in a population with widespread vaccination, the disease struggles to spread and the chains to others are cut. However, the effect of herd immunity is significantly dampened at each level of declining vaccination rates.
Essentially, the decision to not vaccinate affects the whole community, not just the individual.
"Once you read a high enough level of vaccination, the disease gets effectively roadblocked. It can't spread fast enough because it encounters too many vaccinated individuals, and so the majority of the population (even the unvaccinated people) are protected," the creator explains on Imgur.