This is a trivial argument. The benefits of vaccination is both individual and that a large population of immunised individuals The idea of herd-immunity is a large percentage of the population is immunised the chances of disease spreading is minimised. [0]
Vaccinations are effective because individuals taking vaccinations develop immunity and if they come into contact with antigens again, anti-bodies are produced to fight. This is important for infants, who if exposed to an antigen, the time taken and effectiveness of response is weak. [1]
References
[0] http://www.nhs.uk/Conditions/vaccinations/Pages/How-vaccines...