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.