Supporters of the anti-vaccine movement question the safety, efficacy and necessity of the very medicines that have so greatly reduced our children's risk of catching a host of once-common but potentially very serious infectious diseases, such as mumps, measles and whooping cough.

And then there's polio, the disabling, sometimes fatal virus that was every American parent's worst nightmare until effective vaccines were developed in the 1950s — and which still infects children in the developing world.

Some who oppose vaccines are well-meaning parents who have come to believe — wrongly in the view of mainstream medical science — that the medicines are to blame for their own children's health problems, especially in the case of autism.

What they don't realize is that refusing vaccinations jeopardizes not only their own children's health and that of every unvaccinated child in the community, it also undermines a core principle of global health: that vaccines are essential to safeguard all children against disease.

The anti-vaccine movement is quick to publicly criticize anyone it deems to be a shill for the pharmaceutical industry.

Which brings us to "Invisible Threat," a documentary produced by a group of broadcast journalism students at Carlsbad High School. The film takes an unbiased look at the debate over vaccine safety. It includes interviews with physicians; parents who believe vaccines are linked to autism; and parents who have lost children to vaccine-preventable diseases. After considering both sides and weighing the evidence, the students conclude that vaccines are safe, effective and tremendously important. What slight health risks vaccines may pose are vastly outweighed by the good they do.

A no-strings-attached grant of $60,000 from several San Diego-area Rotary clubs in 2012 funded the project, and the sponsors are proud of the results. Unfortunately, controversy delayed the film's public release until last month, when it was posted online.

Anti-vaccine groups say the film is propaganda for the vaccine industry. In a press release, one group cited the Rotary grant as evidence. Why? Because Rotary "receives large grants from the Bill & Melinda Gates Foundation, a major investor in vaccines." In truth, both Rotary and the Gates Foundation are "major investors" in improving children's health worldwide. Since 2007, Rotary's collaboration with the Gates Foundation has raised nearly $763 million, funds that Rotary dispenses as grants to the World Health Organization and UNICEF to fight polio worldwide. The oral polio vaccine is the primary weapon.

As the students report, polio — now so close to eradication — is still only the proverbial plane ride away, placing every unvaccinated child at risk. Even kids in Southern California. In 1952, polio paralyzed a record 21,000 Americans, most of them children. Do we really want to relive that nightmare?

Opposition to vaccines is not unfamiliar to Rotary and its partners in the Global Polio Eradication Initiative, which since 1988 has reduced the incidence of polio by more than 99 percent. It is true that misperceptions and rumors about the polio vaccine sometimes cause parents in developing countries to refuse immunization. Such challenges are anticipated and overcome.

In recent months, however, religious extremists with political agendas — most notably in Pakistan and northern Nigeria — have gone far beyond fomenting fear and distrust. They have actually attacked polio vaccination workers, killing dozens. This is reported in "Invisible Threat."

A concern now is that the noise generated by the anti-vaccine movement here will be heard by the extremists attacking health workers abroad. The last thing needed at this critical juncture of the polio eradication effort is for a violent fear-monger to point to a news headline and tell families, "Look, even American parents fear the vaccines."

Such a scenario would only further jeopardize the health of children denied access to lifesaving vaccines, while increasing the danger faced by the brave health workers dedicated to protecting them.

It is completely understandable that parents of children with unexplained health problems are desperate for answers. But as "Invisible Threat" reports, the weight of medical science comes down squarely on the side of vaccines.

To quote astrophysicist Neil deGrasse Tyson, "The good thing about science is that it's true whether or not you believe in it."

This op-ed first appeared in the San Diego Union-Tribune