List 4 facts about vaccines in relation to bacteria

In the past 60 years, vaccines helped eradicate one disease (smallpox) and are close to eradicating another (polio).[1]
Vaccines prevent more than 2.5 million deaths each year.[2]

Scientific studies and reviews continue to show no relationship between vaccines and autism.[3]

New and underutilized vaccines could avert nearly 4 million deaths by 2015.[4]

Vaccines cause “herd immunity,” which means if the majority of people in a community have been vaccinated against a disease, an unvaccinated person is less likely to get sick because others are less likely to get sick and spread the disease.[5]

Wikipedia aswell can be used to solve the following questions