What are the chances that the noted anti-vaxxers Donald Trump and Robert F. Kennedy Jr. would make common cause to undermine Americans’ health in their pursuit for the presidency?

It didn’t take much hindsight to say the answer is 100%. But there’s no need to speculate any longer — not since this weekend, when Trump and Kennedy both associated themselves with policies that would bring vaccine-preventable diseases such as polio back to the United States.

We’ve already seen that the embrace of pernicious anti-vaccination claptrap by unscrupulous politicians and government officials has had detectable impacts on public health. The Centers for Disease Control and Prevention is now reporting 41 cases of measles, for which a vaccine has been available since 1963, in 16 states.

That includes 10 cases in Florida, where public health comes under the jurisdiction of Surgeon General Joseph Ladapo, a leading quack and established anti-vaccine activist.

Resistance or refusal of COVID vaccination, plainly due to anti-vaccine propaganda, has kept the vaccine rate alarmingly low.

In only one state, Minnesota, did the percentage of population that has received the latest updated booster exceed 20% as of the end of last year. In Florida, the adult booster rate is an appalling 7.7%. (In California, it’s 14.2%, which isn’t something to be particularly proud about.)

As I’ve reported, as many as 200,000 Americans may have died unvaccinated from COVID since the vaccines were approved in early 2021 — nearly 1 in 5 of the roughly 1.2 million American deaths from the disease. An average of nearly 20,000 Americans a week were hospitalized for COVID during February.

Now let’s take a look at what Trump and Kennedy have been up to. We’ll start with Trump.

At a campaign rally in Richmond, Va., on Feb. 2, he said this, referring to the policy he would implement as president: “I will not give one penny to any school that has a vaccine mandate or a mask mandate.”

Trump’s words elicited febrile cheers from his Virginia audience, which may be a sign of what I earlier identified as the phenomenon of “herd stupidity” connected with the anti-vaccine movement.

Did these people have any conception of what they were cheering? (We can assume that Trump didn’t.) Did they cotton on to the fact that Trump was advocating depriving all Virginia public and private K-12 schools, nursery schools, child care centers and home schools of federal funding?

We know that would be the consequence of his pledge, because we know that Virginia requires children attending any of those institutions to be vaccinated against 15 diseases, with boosters where appropriate. Virginia’s mandated schedule, like those of every other state, follows the recommendations of the CDC, which calls for some vaccinations within a month or two of birth.

Trump issued his ukase against vaccine mandates right after declaring at the Richmond rally that he would “sign a new executive order to cut federal funding for any school pushing critical race theory, transgender insanity, and any other inappropriate racial, sexual, or political content onto our children,” thus covering pretty much the entire right-wing culture battleground, almost all of which is based on manufactured outrage.

In context, Trump’s opposition to vaccine mandates falls into the category of glorifying individual “freedom” over the communal interest. As I’ve written before, opposing vaccine mandates as a substitute for opposing vaccination itself is a fundamentally incoherent position — little more than garden variety small-government Republican ideology almost invariably invoked to protect the interests of the “haves” over the “have-nots.”

What makes it incoherent is that mandates do work. They’ve saved the lives of millions of schoolchildren who would otherwise be exposed to deadly diseases at school and play.

During the COVID pandemic, requirements that people provide evidence of vaccination before attending public events or entering restaurants or bars were associated with heightened vaccine rates abroad. Employer mandates in the U.S. have raised vaccination rates at workplaces, as United Airlines showed.

Now let’s turn to Robert F. Kennedy Jr., whose campaign for president has allowed his dangerous anti-vaccine hogwash to be mainstreamed into the body politic like an IV drip of strychnine. His pitch so bristles with disinformation and pseudoscience that it’s been disavowed by virtually his entire family, whose name has been synonymous with progressive politics and policy for generations.

Children’s Health Defense, the anti-vaccine organization Kennedy founded and chairs, last week platformed a fatuously inaccurate 2013 book claiming that polio isn’t caused by a virus and that the polio vaccine “doesn’t work.”

The book was conclusively debunked long ago. But last Tuesday, the organization published an interview with its co-author Suzanne Humphries, in which she repeated her claim that polio is caused by toxins, not the virus.

“According to Humphries, there are no worthwhile vaccines, not even smallpox or tetanus, and certainly not the polio vaccine,” the interview read.

One telling factor about this interview is who conducted it: Joseph Mercola, a notorious dispenser of health disinformation who, I reported in 2012, was making millions “from hawking ‘organic’ nostrums and casting doubt on medical science.”

By then, Mercola had attracted regulatory warnings from the Food and Drug Administration on three occasions — twice for marketing what the FDA described as illegal drugs and also for touting thermography as an alternative to mammograms for breast-cancer screening, for which the FDA said it was not effective, and for what the FDA said were other unsupported diagnostic claims.

The FDA warned Mercola again in 2021 for hawking unvalidated nostrums as purported treatments for COVID.

Mercola also appeared on the list of the “Disinformation Dozen” published in 2020 by the Center for Countering Digital Hate — 12 individuals who together accounted for as much as 65% of the anti-vaccine content on social media. Kennedy also appeared on the list.

The truth, of course, is that vaccines work. Polio became a massive threat to public health in the 1940s and 1950s, with a per capita infection rate in the U.S. that reached 87.2 per 100,000 population in 1952, sending tens of thousands of children to the hospital and killing a half-million people per year worldwide during those decades.

Jonas Salk’s polio vaccine underwent a massive trial involving 1.6 million children in the U.S., Canada and Finland in 1954; the vaccine was licensed in 1955.

Salk became an international hero, the more so because he refused to patent the vaccine or profit from its distribution. In 1952 the U.S. had 79,000 polio cases, including 21,300 that led to paralysis, and 3,145 deaths. By 1960 the cases had declined to 2,525 with only 230 deaths. In modern times polio cases have all but disappeared — thanks to vaccination.

The same phenomenon occurred with measles. In 1958, the U.S. saw 763,000 cases and 552 deaths. By 1968, a few years after the vaccine became available, there were 22,231 cases and 24 deaths.

Thanks to immunization mandates, even the most recent spike in cases — triggered by an unvaccinated visitor to Disneyland in 2019 — reached only 1,274 cases.

What makes anti-vaccine propaganda so insidious is that it exploits public inattention. Vaccines have something in common with baseball umpires and football referees — when they do their jobs right, they become almost invisible.

“Vaccines are a victim of their own success,” the eminent vaccine expert Paul Offit told me last year. “When vaccines work, nothing happens.”

The best testament to the success of vaccines may be the disappearance of vaccine-preventable diseases from the everyday concerns of families, especially those with children. Smallpox has been eradicated from the face of the Earth. No one in developed countries has had reason to fear measles, whooping cough, diphtheria or polio for decades.

That also means that the public has forgotten what made some of these diseases so fearsome.

Measles has been reduced in public estimation to a nuisance fever. But it’s an exceptionally dangerous and contagious disease that can explode in communities in which the vaccination rate falls below 95% — whether because of complacency or due to the long-refuted and fraudulent claim that the MMR (measles/mumps/rubella) vaccine causes autism.

At the Florida public school that has become the epicenter of that state’s outbreak, the vaccination rate was lower than 90%.

Those whose memories or historical knowledge don’t go back to the mid-20th century may need reminding that polio was a uniquely devastating disease in the 1940s and 1950s.

“No disease drew as much attention, or struck the same terror,” medical historian David Oshinsky wrote in his Pulitzer Prize-winning 2005 book about the period. “And for good reason. Polio hit without warning. There was no way of telling who would get it and who would be spared. It killed some of its victims and marked others for life, leaving behind vivid reminders for all to see: wheelchairs, crutches, leg braces, breathing devices, deformed limbs.”

Philip Roth, in his harrowing 2010 novel “Nemesis,” gave a street-level view of how the disease upended daily life in his native Newark, N.J., during the years when no one knew how it was transmitted and there was no vaccine:

“We were warned not to use public toilets or public drinking fountains or to swig a drink out of someone else’s soda-pop bottle or to get a chill or to play with strangers or to borrow books from the public library or to talk on a public pay phone or to buy food from a street vendor…. We were to keep our distance from anyone who looked sick or complained of any of polio’s telltale symptoms.”

That should underscore the indescribable folly of the anti-vaccine campaigning by Trump and Kennedy. They’re playing with fire, and it’s American families and their children who will be burned. Their efforts to make the world safe again for measles and polio should terrify you.