evidence: Also called rubeola, measles spreads easily and can be serious and even fatal for small children. While death rates have been falling worldwide as more children receive the measles vaccine, the disease still kills more than 200,000 people a year, mostly children. [...] You may need the measles vaccine if you're an adult who does not have proof of immunity and: [...] Promoting and preserving widespread immunity. Since the introduction of the measles vaccine, measles has virtually been eliminated in the U.S., even though not everyone has been vaccinated. This effect is called herd immunity.