DR. JAY Gordon, a pediatrician in Santa Monica, Calif., appeared in a “CBS Evening News” broadcast the other day, talking about the measles outbreak that began at Disneyland and now has infected 67 people in 11 states. Dr. Gordon has signed “personal belief exemptions” allowing parents in California to avoid vaccinating their children against the disease. “This measles outbreak does not pose a great risk to a healthy child,” he said. “And quite frankly, I don’t think it poses any risk to a healthy child.” He added that measles “is an almost always benign childhood illness.”

This thinking is dangerous. Measles is a highly infectious, acute viral illness that threatens people who are unvaccinated. Dr. Gordon would be right to say it is not a great risk to children who have been inoculated. But he and others who enable people to avoid vaccination are trafficking in poor information that could lead to more cases of a disease that was eliminated in the United States 15 years ago.

Is measles “benign”? The Centers for Disease Control and Prevention says measles “can lead to severe complications and death” and “even patients who experience uncomplicated acute measles have a small risk for developing a devastating neurologic illness . . . years after their infection.” Measles is common elsewhere in the world, with about 20 million cases reported each year and 122,000 deaths. Before vaccination began in 1963, about 3 million to 4 million people got the disease each year in the United States, of whom 400 to 500 died, 48,000 were hospitalized and 4,000 developed brain swelling. That does not fit our definition of benign.

Last year, the United States experienced 644 cases of measles in 27 states and 23 outbreaks. This is the greatest number since elimination — zero transmissions from one person to another for a whole year — was declared in 2000. What is happening is that unvaccinated Americans and foreigners are bringing the virus to the United States after becoming infected abroad. There are outbreaks in Europe, Africa, Asia and the Pacific; last year most of the cases brought into the United States came from the Philippines, which has been struggling with a large outbreak. While it isn’t certain how the outbreak began at Disneyland, experts say a visitor carried it into the park from overseas between Dec. 15 and Dec. 20. Others were exposed, including at least five Disney employees. Just one infected person can spread the virus to others. According to the Centers for Infectious Disease Research and Policy at the University of Minnesota, the genotype linked to the Disney outbreak is circulating in 14 countries around the world.

There is an effective shield in the United States. The measles, mumps and rubella vaccine works and has a 50-year safety record. Certainly there are enough serious public-health threats today in the United States that a new one should not be created out of a virus that was already eliminated. Those who refuse to vaccinate are wrong. They endanger themselves and those around them.