I’m currently in the masters in public health program at Johns Hopkins University and am taking my first course in epidemiology. I have my first midterm tomorrow and among the many concepts the professors want me to understand is herd immunity.
Herd immunity is the ability to resist an attack of a disease because the majority of the members are immune to it. Disease passes from person to person so when a large portion of the population is immune — most likely through immunizations — this protects those who aren’t immune by decreasing the likelihood a susceptible person will come in contact with the disease.
I hope that was review for the clinicians. But for me, though I had been reporting on health care for four years, this was a new concept. It helps put the importance of mass vaccinations into context. Immunizations don’t only protect those who receive them, but the entire population.
That’s why this seemingly growing movement by parents not to immunize their children is so worrisome. I want to know why public health experts have not taken a stronger, more public position about the importance of immunization.



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