“To protect those who cannot be vaccinated, community or “herd” immunity requires at least 90% of the population to be immunized (95% for highly contagious diseases such as measles or pertussis).”
Not true, in three ways:
- The 90% number is not taken from a study; instead, it’s a number that is a goal of the Healthy People 2020 Government Initiative. The fine print of the AAP policy admits that “there is a variance for levels of immunization required to generate community immunity specific to each disease and vaccine…” The 90% number is simply “generally understood,” not science-based.
- The 95% requirement for measles immunity is often quoted, yet does not have enough research studies to back it up, and the AAP doesn’t furnish any such study in its policy statement.
- The biggest lie of all: the 95% requirement for pertussis herd immunity. The AAP knows full well that the pertussis vaccine (DTaP) doesn’t affect herd immunity at all; it only reduces the severity of disease in each individual who gets sick (and it’s only about 80% effective at that). The germs still infect tens of thousands every year, and are contagious from every one of them, regardless of vaccination status. In fact, 90% of children who caught pertussis in CA in 2014 were vaccinated according to the CA Dept of Public Health. The CDC even states unvaccinated children “are not the driving force behind the large scale outbreaks.” Instead, it is “circulation of the bacteria, waning immunity, and [genetic changes in the bacteria which make them resist the vaccine]” that are responsible.
— Immunity Education