Why are vaccinations important?
Because of vaccinations, some serious diseases like polio are rare or nearly non-existent nowadays. Certain diseases, such as smallpox, have been completely eradicated. Vaccinations are also an important way to prevent the spread of highly infectious diseases such as measles. They can only have this effect (known as herd immunity) if most of the population has been vaccinated. This protects people who are at particular risk, such as babies or chronically ill people who can't (yet) have the vaccination.