The school year has begun, and with that, parents have been stocking up on the usual school supplies and clothing for the coming year. What too many have neglected, however, is the most important preparation kids can have – current and complete vaccinations.

For any parents behind on that score, or simply unsure, now is the time to ensure the kids have all their shots. New notebooks, pencils and erasers are fine, but they offer no protection against some of the biggest threats children face.

State law requires everyone attending a Colorado school or licensed child care center be vaccinated against a series of diseases. Included are hepatitis B, diphtheria, tetanus, pertussis, measles, mumps, rubella and chicken pox.

Unfortunately, the law also allows for exemptions, not only for valid medical reasons but for “personal or religious beliefs.” Actual religious objections are rare, meaning the overwhelming number of exemptions are simply personal. That is to say they are based, not on science, medical knowledge or historical experience, but on rumor, hysteria and minor celebrities’ bogus assertions.

The most egregious of these is the supposed link to autism. That claim stems from one report that has been shown to be fraudulent and the simple coincidence that the symptoms of autism often appear at about the same age children are vaccinated. Any tie between autism and vaccines has been repeatedly debunked by legitimate researchers.

What has been proven – repeatedly, obviously and for all to see – is the effectiveness of vaccines in preventing disease. But memories are short and a diminishing number of Americans have personally known victims of polio or someone who lost a loved one to what are too often dismissed as “childhood diseases.”

When vaccination rates fall below 95 percent the population loses its herd immunity, which protects susceptible individuals. According to the Center for Disease Control, for the 2013-14 school year only 82 percent of Colorado kindergartners were vaccinated for measles.

That is unacceptable. Colorado tightened its rules on exemptions somewhat beginning this year, but more must be done. And the most important step is the simplest: Get all children vaccinated.