Unlike the recent outbreak of enterovirus D68, which involved more than 1,000 confirmed cases, with many hospitalized in ICUs, a few deaths and dozens paralyzed, about 150 cases of measles have the nation in an uproar. People are clamoring for someone to blame, such as parents who do not vaccinate their children or doctors who suggest that vaccines are not an unmixed blessing.

Some facts: Measles is extremely contagious even before a person is obviously sick. It can cause complications, even death. It was declared “eliminated” in the U.S. in 2000, with sporadic cases traced to persons who had been in an endemic area. According to the World Health Organization, the number of cases per million people in 2011 was, for example, 227 in Africa, 1.5 in the Americas, 61 in the eastern Mediterranean, and 43 in Europe.

Some questions:

Can my child get measles from an unvaccinated child? Your child can get measles only from someone who has measles. Contrary to Michael Reagan’s uneducated comment, unvaccinated children are not “Typhoid Marys.” They are very likely to get measles if (and only if) exposed, but vaccinated people also get and can transmit measles. In fact, in some outbreaks, the majority of patients had been fully vaccinated. Unlike natural immunity, vaccine immunity lasts only a few years. Repeated boosters lose effectiveness.

What if my child does get measles? He will be pretty miserable for up to 3 weeks. Then, about 999 times out of 1,000, he will fully recover and be immune for the rest of his life. If the child is a girl and later has a baby, she will pass along her antibodies, which will protect the baby during the first 12 to 15 months when he is most vulnerable and can’t be effectively vaccinated.

Hasn’t the vaccine saved millions of lives? In the U.S., deaths from measles fell by 95 percent between 1915 and 1958. Vaccine became available only in 1963. The complication rate then was about 1 in 3,000, when most people had measles between ages 5 and 9. But now more cases occur in infants and adults, who have worse outcomes.

What about population (“herd”) immunity? More than 90 percent of American children receive MMR, although there are areas where more parents refuse it, dropping the rate to as low as 50 percent. Because adults’ immunity has waned, we may have less population immunity than in 1960.

Is the measles vaccine safe? Like all drugs or medical treatments, there are potential adverse effects. Read the package insert. Most children do fine with the vaccine, but some do not. Authorities assert categorically that the measles vaccine does not cause autism, although they don’t know why the autism rate has increased from 1 in 10,000 to 1 in 42 boys and 1 in 189 girls. Not everyone is convinced by the studies that fail to show a vaccine link.

Don’t the risks of disease greatly exceed the risks of vaccine? It depends. Now, the opposite is believed for smallpox, and you can’t get smallpox vaccine. But if some of the tons of weaponized smallpox were to be used, the picture would change dramatically. The risk of death from disease is the probability of death (or some complication) if you get the disease multiplied by the probability of getting the disease. At the moment, the risk of getting smallpox appears to be zero. Before the outbreak, the risk of measles was close to zero, but that has now changed, though not by very much.

What is the probability (risk) of serious vaccine side effects? That is not so easy to say. Data are limited, and there is individual variation.

What is a concerned parent to do? I suggest asking your doctor. Find a doctor you trust, who will answer your questions respectfully. There are many factors, including our current nearly total dependence on vaccine-based immunity.

What we don’t need to do is to treat unvaccinated children like lepers, excluding them permanently from school or public places, even if they have had no exposure, as some zealots demand. It might make more sense to temporarily exclude any susceptible persons who had been, within 21 days, in a place having an outbreak (Disneyland, the Philippines, etc.). That would include persons whose vaccine immunity has likely waned.

Let us not be distracted from concerns about imported diseases, such as enterovirus D68, for which there is no vaccine and for which a chronic carrier state might exist.

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