There have been zero cases of measles in Minnesota this year, no thanks to me.

Measles is back in a big, dumb way. We’ve seen more than 760 cases across 23 states this year. It’s in Iowa and it’s on airplanes and it’s on that cruise ship full of Scientologists down in the Caribbean.

Minnesota is surrounded. And our defenses are spread thin.

A third of Minnesota schools have kindergarten vaccination rates so low they’ve lost the herd immunity that protects the unvaccinated along with the vaccinated.

The same herd immunity, it turns out, that was protecting me.

Don’t ask me how I ended up with no immunity to measles. I’ve had my shots. But my doctor did a blood test to see if I’d ever had chickenpox. The results came back: immune to mumps, immune to German measles, not immune to chickenpox, not immune to measles.

Herd immunity protected me. It was my turn to protect the herd.

I scheduled a quick appointment and a nurse gave me a fresh hit of the MMR vaccine while she was immunizing me against chickenpox. She assured me I was at least as brave about it as the babies she usually vaccinates.

“We really rely on each other to vaccinate,” said Lynn Bahta, the Minnesota Department of Health’s immunization clinical consultant, and one of the medical experts working to convince parents not to walk away from a safe, effective cure to a virulent and potentially lethal disease. “We can keep a wall of protection up for those who can’t take the vaccine or are too young to get it.”

There are cracks in that protective wall, spreading from junk science and garbage social media posts that try to tell you the disease is somehow safer than the cure.

Millions of Americans used to come down with measles every year. The disease was so contagious, kids were almost guaranteed to catch it before their 15th birthday.

Every year, tens of thousands of American children were hospitalized with measles. Every year, measles killed 450 to 500 of them.

Then, a miracle. A scientist named John Enders developed a vaccine to fend off the measles virus. By the year 2000, the United States had eradicated measles. New millennium, no reported cases on our shores.

We banished a deadly disease. And then we just let it back in.

Antivaxxers may approach you at this point, muttering about vaccine injury and posting links to Facebook videos in the online comments.

Avoid them as you might avoid someone who stands on solid ground while arguing that gravity is just a theory.

We don’t have time to argue with people who’ve made up their minds.

Measles is spreading. Measles is killing.

It killed 110,000 people worldwide — most of them children younger than 5 — in 2017, according to the World Health Organization. It’s killed five people in vaccination-shy Europe this year.

The measles vaccine is safe and effective. But not everyone can get vaccinated. Tiny babies, people with weakened immune systems, people who are allergic to the vaccine ingredients, kids whose parents watched a scary Facebook video; none of them is safe.

The Rippy family isn’t safe.

At the start of every school year, Linsey Rippy sends a note about vaccinations to other parents in her daughters’ classes. Both her young daughters have undergone heart transplants and are on medication that suppresses their immune systems and leaves them vulnerable to disease.

“The people that are around my kids have to be vaccinated, so we know that we are giving them as much of a safety net as possible,” she said earlier this year, when Star Tribune reporters Glenn Howatt and MaryJo Webster analyzed the gaps in Minnesota’s vaccine safety net.

It’s been two years since Minnesota’s last big measles outbreak. Seventy-five people got sick, and a quarter of them ended up in the hospital.

And still, Minnesota is one of those states that allows parents to opt out of vaccinating their children for no medical reason beyond “personal belief.” Since that looks unlikely to change in the final weeks of this legislative session, we’re going to have to protect the Rippy kids ourselves.

The only way to protect them is to roll up our sleeves, and our kids’ sleeves, and measle-proof this herd.

If measles wants to hurt any of us, it’s going to have to come through all of us.