Herd Immunity

In the 1960s, nearly everybody was vaccinated.  Our parents grew up before many of the vaccines we got were even available, and saw the devastation wrought by polio, diphtheria, rubella, mumps, etc.  The people who developed the vaccines that made these diseases and others rare were heroes. 

For a number of reasons in the time since then, people have opted to not be vaccinated against many of these devastating diseases – and in some cases to not vaccinate their children.  They’ve been able to do this with relative impunity because they were protected by ‘herd immunity’; enough of us were vaccinated that, even when the rare person contracted one of these diseases, there wasn’t the reliable chain of contagion required to sustain an epidemic. 

Well, those chickens have come home to roost.  Complacency—combined with traditional beliefs and skepticism for scientific data—have led to increasing numbers of people opting out of immunizations.  Now there are enough gaps in herd immunity that a chain of disease vectors are passing on some of these diseases.