In 1721, a devastating smallpox epidemic struck Boston. Nearly half its residents fell ill. Hundreds died. In his diary, the Rev. Cotton Mather wrote that the town had become almost a "Hell upon Earth.”

Onesimus, an African man sold into slavery to Mather, recalled a method he had witnessed in Africa: Inoculating healthy people with a small amount of infectious material would produce only a mild infection, and make them immune to the disease.

Onesimus’ method, termed variolation, predated Edward Jenner’s experiments using a milder virus, cowpox, to vaccinate against smallpox in 1796. But Mather believed Onesimus. The preacher used his influence to promote variolation ‒ and was derided for it. He finally persuaded a doctor named Zabdiel Boylston to perform it. The technique saved hundreds of lives.

This American story illustrates a recurring pattern of medical progress. A new idea is disparaged as heretical, and the true-believing maverick must endure ridicule to demonstrate its worth. Finally, sometimes after decades, acceptance is achieved. This pattern repeats, but not in a predictable or linear fashion. Innovation can emerge from unlikely sources and often depends on individualists willing to act before possessing full knowledge of why their intervention actually works.

National Doctors' Day honors physicians and medical innovators

National Doctors’ Day, observed on March 30, is designated to commemorate the dedication of physicians and medical innovators such as Crawford Long.

In the 19th century, Long was a country doctor in Georgia who noticed that those experiencing pleasure from ether could injure themselves without pain. This sparked an epiphany. On March 30, 1842, he used ether to sedate a patient whose neck tumor he removed. Long had discovered surgical anesthesia, among America’s first major contributions to medicine.

About the same time, Dr. Oliver Wendell Holmes argued that puerperal fever, which killed countless mothers after childbirth, was caused by physicians’ unwashed hands. The germ theory did not then exist. Eventually, science would prove him right.

By the turn of the 20th century, American medicine became more systematic. At Johns Hopkins Hospital in Baltimore, luminaries like William Osler and William Halsted modernized clinical science, bedside teaching and surgical techniques.

But if science laid the foundation, it was America’s capacity for scale that would result in global impact:

Insulin was discovered in Canada in 1921, but it was the U.S. pharmaceutical industry, led by companies like Eli Lilly, that developed methods to mass produce it, transforming diabetes from a death sentence to a manageable chronic illness.

Penicillin was discovered in Britain in 1928, but the United States was the first to produce it at scale ‒ at a Department of Agriculture lab in Peoria, Illinois ‒ in time to save the lives of countless World War II soldiers fighting overseas.

And a combination of U.S. science and scale fueled the development and distribution of the polio vaccines developed by Jonas Salk and Albert Sabin in the 1950s, drastically diminishing one of the most feared diseases in history.

The lesson of this era is clear: The United States excelled not only at inventing treatments, but also in building the systems ‒ industrial, governmental and academic ‒ to deliver them to millions.

Turning science fiction into medical reality

America's scientific advances then shifted the focus of medical discovery again, this time toward the molecular foundations of life.

The discovery of reverse transcriptase revealed how certain viruses replicate, opening the door to future treatments of diseases like HIV.

The identification of proto-oncogenes transformed our understanding of cancer, showing that it arises from dysregulation of normal genes rather than solely external factors.

Today, this sea change has accelerated into something even more revolutionary: the ability to design and program biological systems. In recent years, American science has turned ideas once considered science fiction into reality. CAR-T therapy involves reengineering a patient’s own immune cells to recognize and destroy cancer. CRISPR gene-editing technology permits precise editing of DNA, opening the possibility of correcting genetic diseases at their source.

Meanwhile, mRNA vaccine platforms, built upon decades of research by scientists like immigrant Katalin Karikó, enabled America's rapid development of vaccines during the COVID-19 pandemic.

What unites these modern advances with earlier ones is not just their ingenuity, but also the conditions that made them possible. Time and again, American medicine has benefited from an openness to new ideas ‒ wherever they originate from.

Onesimus’ knowledge of variolation, once dismissed, proved lifesaving. Immigrant scientists have made outsized contributions in every medical field. Breakthroughs have flourished, not in isolation, but through the exchange of ideas brought together by scientists in America’s melting pot of global diversity.

As the United States moves into the future, advances in gene editing, personalized medicine and the integration of artificial intelligence into health care offer enormous promise. But future headway will depend on preserving the conditions that have spurred progress for centuries: openness to new ideas, willingness to take risks, strong institutions and industrial capacity that can bring lifesaving innovations to the world.

Dr. Andrew Lam is a retina surgeon and an assistant professor at the University of Massachusetts Medical School. He is the author of "The Masters of Medicine: Our Greatest Triumphs in the Race to Cure Humanity’s Deadliest Diseases.”

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