The measles are back with a vengeance, and so are the protests.

So far this year, the Centers for Disease Control and Prevention is tracking six outbreaks affecting more than 100 people, with 68 cases in the Pacific Northwest alone, according to the CDC, Associated Press and Washington Post.

Yet despite the demonstrable success of vaccines—the near worldwide eradication of polio a case in point—anti-vaccination fervor is spreading like a virus. Some lawmakers are pushing legislation that would allow parents to opt out of childhood vaccinations, a move that could jeopardize not only the health of their children but others with whom they come into contact.

None of this is new. In 1897, Dr. Richard Slee, founder of the firm that would evolve into the U.S. operations of biologics company Sanofi Pasteur, faced a similar backlash when he introduced to the United States a vaccine to prevent smallpox.

The story of his struggle is told in The Spirit of Swiftwater, a chronicle of the fight to eradicate vaccine-preventable disease in the 20^th Century. The story is a timely reminder of the efficacy and controversy of this form of medicine:

The new science of immunology had proven vaccines could save lives. It had progressed quickly from the late 1700s, when British physician Dr. Edward Jenner discovered that smallpox could be prevented by inoculating people with the substance from cowpox lesions. The vaccine worked. According to the New York City Health Department, the death rate from smallpox in 1869 was 21.9 per 100,000 people. In 1876, New York’s Vaccination Corps fanned out to inoculate the city. The following year, the death rate per 100,000 people had dropped to 0.18.

That did little to convince parents who’d heard reports that bacteria from the lesions had caused serious infections in some children.

Even with a tacit endorsement from the federal government, the fledgling biologicals industry still faced a daunting problem not related to finance — a public backlash against vaccination. Despite the reduction in mortality that immunization had brought to the nation, not all of its citizens were convinced this was good public policy, or even effective health care.

In 1908, a medical doctor from Niagara Falls, New York, J. W. Hodge, wrote that compulsory vaccination was “the crime of the century,” citing evidence that the process not only violated an American’s freedom but that it was ineffective. “The accumulated experience of more than one hundred years has conclusively demonstrated that vaccinia neither prevents smallpox nor mitigates that disease when it attacks the vaccinated.”

Slee countered those attacks and others in a letter to the Bergen County, New Jersey, Medical Society in 1910:

The growth of the anti-vaccination societies in this country is largely due to the undeniable fact that the protection by vaccination was sometimes followed by results that were more serious than would be a mild attack of smallpox. We are now passing through the transition state, so to speak, and in a short time physicians will begin to realize that the regulations of the government are wise and that the failures from time to time are more than offset by the undeniable elimination of many severe and unpleasant sequelae [an abnormality following a disease, like paralysis following polio].

Unless lawmakers take the decision out of the hands of the experts.

[Measles vaccine doesn’t cause autism, says a decade-long study of half a million people.]