The recent measles outbreak should not be happening. Measles was declared eliminated from the US in 2000. In most years since then, less than 100 cases per year were reported.

In 2014, 644 measles cases were reported, with 383 cases concentrated among unvaccinated Amish communities in Ohio. Many of the 2014 cases came in with visitors from the Philippines where an outbreak was in progress. By the end of January 2015, at least 84 US cases have been reported, with most originating from one infected person at Disneyland in California.

As in the 2014 Amish outbreak, those infected at Disneyland were usually unvaccinated. These people took the disease to their homes in California and other states where they will infect others who most often are unvaccinated. The spread will continue until the disease cannot come into contact with a susceptible person.

When vaccination exceeds 93% of the population, the spread of measles slows to a pace near zero. This is called “herd immunity.” Unfortunately we are not quite there. In 2012, 91% of both young children ages 19-35 months and teenagers aged 13 to 17 years were vaccinated. In 2013, there were 17 states where fewer than 90% of children had been vaccinated for measles, and there are some counties where the vaccination rates are very low.

Public health agencies are adamant that the measles vaccine carries extremely low risk of significant side effects and delivers a high degree of immunity (93% with one dose and 97% with 2 doses). Progress in eradicating measles has been halted recently by families that refuse to accept the medical judgment of public health agencies. The resulting flood of children lacking measles immunity has become a pathway for the aggressive virus to hop from one nearby victim to the next.

A few years ago, decisions to skip vaccinations could be blamed on bad information, but the Internet offers everyone who seeks it high quality, science-based, authoritative and easy to read advice that is not connected to antisocial or bizarre agendas. Despite the clear message that vaccination is safe and effective, many families are placing their children at risk by omitting vaccinations.

In 1998, Andrew Wakefield, a British physician, wrongly claimed that vaccination causes autism, instilling panic in some parents. The British medical community thoroughly discredited the research and the physician. Despite vigorous correction of the medical record, “TV personalities” (such as Jenny McCarthy of ABC’s The View) preach about the imaginary vaccine-autism connection. A handful of others denigrate vaccines and orthodox Western medicine, and a surprisingly receptive public is listening to these sermons as if they were equally as valid as science-based medicine.

It is inconsistent with our freedoms to shut down talk fueled by merely bizarre beliefs. However, we have a tradition and duty to take actions that tend to protect children, especially when it does not usurp their parents’ right to raise them lawfully.

Unvaccinated school-age children are at elevated risk of contracting diseases such as Measles, Mumps, Rubella, Tetanus, Diphtheria, Pertussis, Pneumococcus, Rotavirus and perhaps others.  Their risk is elevated while they attend public school where many bacteria and viruses are routinely transferred between children. They will be exposed to far fewer risks if they stay at home.

Since unvaccinated children are far more likely to become infected, having them stay at home will reduce the spread of measles to have students who have been vaccinated (i.e. the 3% to 7% susceptibility among vaccinated people). An “unvaccinated children stay home” policy is precisely what one Arizona and two California schools used to protect students.

This practical measure may draw objections from the anti-vaccination families. They have a right to their own religious or philosophical beliefs. Whether they have a right to elevate the medical risks that their own children face is debatable, but they do not have a right to elevate unrelated children’s risk of contracting preventable diseases.

Alan Daley is a retired businessman who writes for The American Consumer Institute Center for Citizen Research