Nineteen years ago, the United States declared measles to have been effectively eliminated. That didn’t mean there were no cases of the disease, but that there were so few as to be statistically negligible. What brought the Centers for Disease Control and Prevention to that point was the effectiveness of the MMR vaccine, used to inoculate children against measles, mumps and rubella.

Over the following decade, 911 cases of measles were reported in the U.S. There have continued to be a smattering of cases each year, mainly because some people refused to be vaccinated or let their children be, and because world travel is far more common than in past centuries. More than half the cases of measles seen in the U.S. over the past decade can be traced to uninoculated Americans being exposed to the disease while abroad.

And those cases are rising. Monday, the CDC reported there have been 387 cases of measles in the U.S. so far this year. That’s more than in all of 2018. New Hampshire is among the 15 states where cases have arisen, but the majority have been in six outbreaks among four states — New York, New Jersey, California and Washington.

In some of those locations, public health officials, rightly concerned the outbreaks might grow, have taken strong action. Rockland County, N.Y., which has had more than 150 cases, has banned unvaccinated youths from any public area; that includes schools.

Why take such drastic action? Well, measles is extraordinarily contagious among those not inoculated. And while it is miserable to endure — including fever, rash, cough, inflamed eyes and runny nose — measles can also lead to pneumonia and, more rarely, seizures, blindness, or inflammation of the brain. Before the measles vaccine was perfected, 400 to 500 people died annually in the U.S. from the disease.

So, it’s well worth getting inoculated, and making sure your kids are inoculated. But, this being America, a nation built upon the concept of “don’t tell me what to do,” many people bristle at the idea that they should do so just because the government says so. They’re not persuaded just because they’re told it’s necessary to safeguard the public.

And that’s what vaccine programs do: The idea is that if enough of the population is inoculated, the disease will die out for a lack of transmitters. And it works. But only if enough people cooperate. For measles, the CDC estimates 95 percent participation will keep the disease at bay.

There are also other reasons some populations don’t do it. Several religious groups, including orthodox Jews and the Amish, refuse inoculation on religious grounds. Unsurprisingly, those groups have specifically been linked to recent outbreaks.

Others, in recent years, have bought into the nonsensical “anti-vax” movement — refusing to vaccinate their children based on stubbornness and misinformation such as long-ago-refuted “evidence” linking vaccines to autism. That the study cited by these conspiracy theorists was not only disproven, but also its author found to have made up his findings, somehow isn’t enough to persuade them.

The truth is, any vaccine can have terrible side effects for someone. The measles vaccine can cause serious allergic reactions, though they’re very rare. The fatality rate for the vaccine — the incidence of people dying from it — is one in 1 million. By comparison, the fatality rate for measles itself is 0.2 percent, or two in 1,000.

Typically, those victims are children under age 5. And even in areas where almost everyone chooses to inoculate their kids, those vaccinations don’t take place until a child is 15 months or so, meaning all babies are susceptible to exposure. They’re also among the most vulnerable.

Consider, then, a parent who decides not to vaccinate their preschooler, who becomes exposed to measles during a family vacation. Then the parent drops the child off at school, where other parents may be carrying their infants while dropping off their own children.

That’s a recipe for disaster, and all the argument that should be needed to ensure everyone gets inoculated.