National Review Editor Rich Lowry’s column in today’s New York Post takes on celebrity Jenny McCarthy and her misguided crusade against vaccinations for childhood diseases:

The former Playboy model and current co-host of “The View” is a leading light of the anti-vaccine movement. She has a boy with autism-like symptoms that she is convinced were caused by the vaccine for measles, mumps, and rubella (MMR). You can credit her passion for her child, sympathize with her heartbreak — and still cringe at her wholly irrational cause.

Ms. McCarthy—who became famous for posing naked and picking her nose on MTV—is apparently influential enough to persuade otherwise responsible parents to put their kids in danger by foregoing vaccinations. McCarthy, and now another former MTV star Kristin Cavallari, have both argued that vaccines cause autism.

Now we are learning that cases of measles and whooping cough, two diseases vaccines had effectively disappeared, are back with a vengeance because parents are refusing to get their kids vaccinated. The effectiveness of vaccines is based on herd immunity:

The whole herd is merely protected if a certain percentage is immunized; mathematical models can be used to determine exactly what percentage of the population needs to be vaccinated to prevent a communicable disease. For example, if approximately 80 to 86 percent of a population is immune to polio, then herd immunity is achieved.

Lowry points out that where vaccination rates have fallen, the return of infectious diseases has followed:

A study in the journal Pediatrics found that the 2010 whooping-cough outbreak in California — when the state had the highest number of cases since 1947 — hit hardest in areas with high levels of nonvaccination. In 2013, measles cases tripled nationwide. Outbreaks were centered in religious communities in Brooklyn, Texas and North Carolina that had resisted vaccination. New York City has another small outbreak right now.

The many celebrities who support Obamacare can be blamed for promoting a bad product that is hurting Americans and the economy. But Jenny McCarthy has taken advocacy of bad medicine a step farther.

Babies too young to be vaccinated have died from the resurgence of these diseases. Shame on any parents who’ve listened to McCarthy and especially shame on her for advocating something that puts American kids in danger.