Community immunity is also known as herd immunity. This takes place when a critical portion of a community is immunized against a contagious disease, most members are protected against that disease because there is little opportunity for an outbreak. Those that are not eligible for the vaccines (for example, infants, pregnant women, or immunocompromised individuals) are able to have some protection because the spread of the disease is contained. This principle applies to a range of human diseases, such as influenza, measles, mumps, rotavirus, and pneumococcal disease.
References:
www.vaccines.gov/basics/protection. Accessed November 30, 2013
Fiarfax County Government. (2011, August 12). Fairfax County's Community Immunity [Video File]. Retrieved from http://www.youtube.com/watch?v=z7CA2YsbUlk