In 1900, 30 percent of deaths in the United States occurred in children less than 5 years of age, mostly from infectious diseases like pneumonia, diarrhea, tuberculosis, diphtheria, and measles. When parents were asked how many children they had, they often replied with the number living and the number dead. By the end of the century, children under 5 accounted for only 1.4 percent of U.S. deaths. That year, Morbidity and Mortality Weekly Reports (MMWR), the CDC’s flagship publication, published “Ten Great Public Health Achievements -- United States, 1900-1999.” Vaccination led the list.

Anti-Vaccine Activists Have A Different View

In addition to exaggerating the vaccination’s risks, anti-vaccine activists tend to minimize or deny their remarkable benefits. For example, in a recent online video posted by his eponymous foundation, Dr. Peter McCollough makes the following claims:

“I worked with best-selling author John Leake, and we looked at this very carefully - 300 years of vaccines. Virtually every vaccine introduced for a disease - that disease was essentially going away or gone, and mortality going… 99% reduced before the first dose of vaccine was ever given. So, the first point is how we conquered these infectious diseases was through sanitation, cleanliness, living conditions. You know, early on, we didn’t even know they were infectious diseases.”

In fact, the world’s first vaccine was discovered 230 years ago, not 300. Improved sanitation, clean water, and living conditions certainly played important roles in reducing child and adult mortality, mostly from enteric diseases. However, McCollough’s claim that virtually every vaccine-preventable disease was “going away or gone” and mortality ”99% reduced" before the first dose of vaccine was given is utter nonsense.

The Protective Power of Vaccines

The most definitive study on this question was published in The New England Journal of Medicine in 2011. it was conducted by faculty of the University of Pittsburgh and Johns Hopkins Schools of Public Health. The database they compiled included all medically documented reports of notifiable disease in the United States dating back to 1888—nearly 88 million cases in all.

Their analysis revealed that disease rates were high before each vaccine was introduced. Afterward, they declined dramatically. A few examples follow.

The world’s first vaccine, against smallpox, was discovered in 1796, but its initial impact was modest due to limitations of 19th-century technology, logistical hurdles, worrisome side effects, and societal resistance. Nevertheless, progress was steady, and the last domestic case of smallpox in the U.S. was recorded in 1949. It persisted in parts of Africa and Asia until 1967, when the World Health Organization (WHO) adopted a highly effective vaccination strategy devised by Dr. William Foege , a CDC field epidemiologist. Over the next 13 years, smallpox was eradicated worldwide.

When vaccines targeting diphtheria (which can suffocate young victims), pertussis (whooping cough), and tetanus (often lethal) were introduced, rates declined slowly at first due to limited uptake. They accelerated when the three vaccines were combined to make the “DPT” (diphtheria–tetanus–pertussis) vaccine in 1948.

Polio terrified American families in the first half of the 20th century because it struck without warning and often paralyzed its victims. When the Salk vaccine was approved in 1955, the nation rejoiced. Parents lined up their children for vaccination, and new cases swiftly declined. Licensure of the Sabin oral polio vaccine in 1961 led to further reductions. Polio was eradicated from the U.S. in 1979.

Measles, a highly contagious disease that can cause pneumonia, brain swelling and immunosuppression, declined rapidly after a vaccine was introduced in 1963. Vaccines against mumps (which can cause meningitis and deafness) and rubella (which can cause birth defects in pregnant women) followed in 1967 and 1969, respectively. However, sporadic outbreaks continued until 1978, when the ”MMR” (measles–mumps–rubella) combination vaccine was rolled out along with two national vaccination programs.

By comparing disease rates before and after each vaccine was introduced, the study authors estimated that more than 100 million cases of contagious disease were prevented by vaccination between 1924 and 2011. This included 40 million cases of diphtheria and 35 million cases of measles.

Decades Of Progress Are Being Lost

As illness and death rates fell, fear of vaccine-preventable diseases dissipated. This allowed antivaccine activists to start shifting the narrative to alleged side effects. Many also minimize or deny vaccines’ effectiveness. Over time, the steady stream of disinformation they produce has convinced a growing percentage of parents to delay or refuse to vaccinate their children.

The appointment of RFK, Jr ., a longtime anti-vaccine activist, as HHS Secretary has galvanized the movement. Reversing decades of bipartisan support for vaccines, Kennedy and his inner circle upended HHS agencies and advisory panels that encouraged vaccination. In his keynote address to Children’s Health Defense on Sep. 17 (with measles cases at a 30-year high), Mr. Kennedy declared: “Let me be clear: you have a strong and steadfast friend in the White House.”

Five weeks before, President Trump signed an executive order recommending that children be vaccinated against 11 diseases rather than the current 17. He also called for splitting the MMR vaccine into three separate shots, defying evidence that the the combination vaccine protects more kids.

The 20th century is often called the “American Century” because the United States emerged as a global leader in political, economic, military, scientific, and cultural affairs. In the first decade of the century, George Santayana wrote this well-known line: “Those who cannot remember the past are condemned to repeat it.”

In our current age of disinformation , Americans must work harder than ever to remember the past. Otherwise, we may fall victim to false narratives. If we allow that to happen, we could find ourselves back where we started in 1900.

I am indebted to Dr. Donald Burke, Dean Emeritus, University of Pittsburgh School of Public Health and Distinguished University Professor Emeritus. I am also indebted to Dr. Harry Hochheiser, Professor of Biomedical Informatics and their colleagues at the University of Pittsburgh for their landmark scholarship and assistance with the graphics in this commentary.

My opinions are my own and do not necessarily reflect those of any past or current employer.