Recently, PBS’s NOVA had an episode on the reemergence of diseases (including measles, whooping cough, and mumps) that had previously been largely eradicated in the US by vaccines, in part because nervous parents are skipping their children’s shots. At least ten percent of parents delay or skip some recommended vaccines, and one percent don’t vaccinate at all. What’s driving people away, and what are the consequences? Those are the questions explored in Vaccines — Calling the Shots, which you may view in full below.
One consequence of reduced immunization rates is the potential loss of “herd immunity” for some diseases. Herd immunity is the protection provided to a community when a critical mass of the population is vaccinated. When a vaccinated person is exposed to an infection, their immunity can break the chain of transmission, protecting the people whom they might otherwise expose if they weren’t vaccinated.
Herd immunity worked to stop a measles outbreak last year in New York City, where a total of 58 cases were identified in two Brooklyn neighborhoods last year. None of the individuals had previously been vaccinated for measles. Measles is airborne and extremely infectious. Up to 90% of exposed, unvaccinated individuals become infected. Thankfully, due to existing high vaccination rates in New York, health officials were able to prevent the outbreak from becoming widespread.
To learn more about herd immunity, visit here.