Public Health Myth #4: Herd Immunity Requires Vaccination

The Truth: Herd immunity through vaccination does not exist. The theory behind herd immunity is that if a given percentage of individuals (usually between 85-96%) are vaccinated, the community is fully immune from outbreaks and the immunized protect those who cannot be immunized. However, many outbreaks have occurred within populations that have been fully immunized, and some research points to the vaccination program as the instigator of outbreaks.

Supporting statistics for this phenomenon include:

2009: over two dozen cases of pertussis in Hunterdon County, New Jersey; all the children infected had been immunized prior to contracting the illness

1994: measles outbreak in Cincinnati; 80% of the children involved had had at least three doses of the vaccine

1989: 2,720 reported cases of measles nationally; 72.5% (1,972 of them) occurred in those who were vaccinated

1989: measles outbreak in a high school in Illinois; 69 cases, 99.7% occurred in those who were vaccinated

1987: CDC reported 2,440 cases of measles among vaccinated children 1986: measles outbreak in Corpus Christi, TX; 99% occurred in children who had been vaccinated

1986: in Kansas; 1,300 cases of pertussis were reported; 90% occurred in those who were vaccinated

1984, measles outbreak at a high school in Waltham, Massachusetts; 27 cases, 98% had documented proof of vaccination against the measles

1971, a rubella epidemic in Casper, Wyoming; 84% (91 of the 125 cases) occurred in vaccinated children

stopmandatoryvaccination Public Health Myth #4: Herd Immunity Requires Vaccination