Its formal name was Rosemary Lake, a small body of water in my hometown to which we kids flocked each summer seeking relief from the heat.

But to this day, I remember it by its ominous nickname: Polio Pond.

To be clear, no one to my knowledge ever actually contracted polio from the murky water – although Dr. Bailot, our family physician, often decried the town-operated swimming facility as a petri dish of childhood infections.

But the name was nonetheless telling: Polio, while on the wane in the late 1950s and early 1960s, still scared the hell out of everyone.

And the vaccine that all but eradicated it in the United States – from tens of thousands of cases to virtually none in a mere decade – left parents far and wide thanking God for this modern-day miracle.

Memories of benevolent old Dr. Bailot, syringe in hand, resurfaced this week with the news that the percentage of Maine children showing up at kindergarten without vaccinations jumped from 4 percent to 4.8 percent over the past year.

No big deal? Guess again.

As Peter Michaud, associate general counsel of the Maine Medical Association and chair of the Maine Immunization Council, told Portland Press Herald reporter Joe Lawlor, the uptick is “extremely distressing.”

It’s also a case study in how times can change. Half a century ago, parents welcomed with open arms the array of vaccinations for polio, measles, mumps, rubella and other serious infectious diseases that had long run roughshod over every level of society.

They had seen what those illnesses could do, how a child could be healthy one minute and paralyzed – or in a tiny casket – the next. To not inoculate your child with these readily available remedies was unthinkable.

No longer. Today, for a small but growing number of parents, the vaccines are the bogeymen. The danger of the diseases they target is overblown. It’s the pharmaceutical companies that are trying to kill us.

They could not be more wrong. Nor could they be more self-centered.

Don’t misunderstand. I have no doubt that these parents love their children as much as my mother loved her four boys and four girls.

But this is not just about them or their kids. It’s about all of us.

Much of today’s anti-vaccine movement stems from “Vaxxed: From Cover-Up to Catastrophe,” a 2016 film that alleges a conspiracy by the federal Centers for Disease Control and Prevention to hide a purported connection between the MMR (measles, mumps and rubella) vaccine and autism.

The film has since been discredited from every corner of the scientific community as baseless, fear-mongering propaganda. It was directed by Andrew Wakefield, who lost his license to practice medicine in the United Kingdom because of serious ethical violations in his anti-vaccine research.

Such as? Well, Wakefield never disclosed that while conducting his since-debunked 1998 study of possible links between the MMR vaccine and autism, he was paid hundreds of thousands of dollars by lawyers looking to sue the vaccine producers.

No matter. Despite that and other transgressions, an anti-establishment star was born.

Which brings us back to those Maine parents who think they’re doing the right thing by not vaccinating their kids and sending them off into the general population.

Two years ago, Gov. Paul LePage vetoed a bill that would require parents with a “philosophical objection” to vaccines to at least consult with a medical professional before opting their kids out of their preschool shots. He wrote nonsensically that the legislation “unwisely leads the horse to water and tries to make it drink.”

LePage also maintained that, while he personally supports vaccinations, parents who opt out “have as much right to their opinions as the parents who choose to vaccinate.”

Their opinions, however, aren’t the problem here. It’s their blinders.

Many in the anti-vaccine crowd maintain that the danger is overblown – the diseases in question are now so rare that the risk of contracting them is outweighed by the perceived (albeit unproven) risk of vaccination.

But it’s precisely because of decades of vaccination that the diseases are so rare. All of society has benefited from diligent adherence to vaccine protocols – including those parents who now turn up their noses at the needles and say, “None for my child, thank you.”

It’s enough to make my dearly departed mother, and millions like her, turn in their graves.

The simple truth is that the “herd immunity” created by vaccines protects us all, including those with compromised immune systems and other medical conditions that legitimately prevent them from getting their inoculations.

Still, herd immunity is a fragile thing. Chip away at it or, worse yet, create clusters of non-vaccinated children – the number of unvaccinated kindergartners exceeded 20 percent in six Maine public schools during the just-completed school year – and bad things inevitably will happen.

To wit: To maintain herd immunity from the highly contagious and potentially lethal measles virus, a society must vaccinate 96 percent to 98 percent of its population.

But according to a 2016 mathematic modeling study published in JAMA Pediatrics, the population exposed to the virus at Disneyland in late 2015 – an outbreak that eventually sickened 145 Americans – had a vaccination rate no higher than 86 percent and possibly as low as 50 percent.

This for a virus that was declared “eradicated” in the United States back in 2000.

Here in Maine, the first measles case in 20 years was reported last month in Farmington – a female who contracted the virus during overseas travel.

Considering that a whopping 90 percent of unvaccinated people exposed to measles end up infected with it, imagine what would have ensued had that patient walked into a kindergarten class where a quarter or more of the students had never received their MMR shots.

And for what?

Because a crusading quack made claims 20 years ago that have never, not once, been backed up by real science?

Because we live in an age when people first decide what they believe and only then seek out the “facts” to back it up?

Because it will never happen to their kid … until it does?

Not too long ago, I drove through my old hometown to revisit my childhood haunts.

Sure enough, Polio Pond is still there. But decades ago, the town actually inserted a separate – and much cleaner – swimming pool into the portion of the lake where our young immune systems once battled Lord knows what.

I saw plenty of kids splashing in the crystal-clear water.

I saw no one swimming on the dirty side.

Chalk one up for common sense.

Bill Nemitz can be contacted at:

[email protected]