Childhood vaccinations are a cornerstone of modern public health. Routine vaccinations have significant health benefits for the person being vaccinated – benefits that may be extended to someone who’s either not protected via vaccination or natural immunity. This protection is referred to as “herd immunity.”
Herd immunity is similar in principle to how a herd of elephants protects their babies. When a herd of elephants encounters danger, the adults form a ring around the babies, facing outward towards the danger. They become a barrier between the danger and the defenseless babies. But for the practice to work, there must be enough adult elephants to circle the baby elephants. If not, then the protection scheme is in danger of breaking down. The same thing happens with herd immunity.