By Jonathan Sadowsky, the Castele Professor of Medical History 

I often start a new class by asking why we should study history. I don’t allow the cliché “History repeats itself,” without specific examples. The history of epidemics provides some: racist scapegoating, denialism, resistance to public health measures, and vaccine hesitancy.

When the COVID-19 epidemic started, historians of medicine predicted ethnic or racial scapegoating, placing the blame on a group for a disease that they did not cause, and persecuting them in retribution. We had studied the scapegoating of Jews during the Black Death and of Irish immigrants during American cholera outbreaks in the 19th century. With COVID-19 this misplaced anger has focused on Asian-Americans, with horrific consequences. Denialism toward the reality or threat of disease is also predictable. In epidemics, some deny the threat because it is economically or politically inconvenient, others for psychological reasons. Public health measures will spark resistance. During the 1918 flu, Americans were also divided about masking. In 19th-century Naples, Italy, public health authorities warned of the dangers of eating fruit; some people responded by eating fruit in flamboyant public displays. Defiance against masks and lockdowns this year were lamentable, but not surprising. “Vaccine hesitancy” is also a recurring theme. Resistance to vaccines is as old as vaccines.

For some vaccination is counter intuitive. Historically, vaccines were made from infectious agents or components of infectious agents. That’s how they work; they have to be similar to the microbe in order to teach the immune system to fend off the disease. But in America, resistance does not come primarily from people who misunderstand the science. Rather, educated and affluent people worry that vaccines are “unnatural.” Hesitancy is also sown by mistrust people have of powerful institutions, such as the government or corporations. Many fear worse health outcomes from the vaccine than the illness; misinformation, like the disproven claim that vaccines cause autism, contributes. The success of the disinformation also has a history, and it frequently lies in the very success of vaccines. As terrible as the current pandemic is, progress in fighting infectious disease has caused collective amnesia about infectious disease, and how precarious life and health were before vaccines became widespread. Ask anyone under 50 about polio and you will see how quickly diseases are wiped from our collective memory after they have been defeated by well-organized distribution of safe and effective vaccines.

Many cite the earned mistrust of American medicine among minority groups as another source of vaccine hesitancy. While unequal and unethical medical treatment of minority groups is both a historical and current reality, so-called vaccine resistance by minorities is more an example of the scapegoating than a description of reality. Distribution of COVID-19 vaccines has lagged in minority communities primarily because of unequal access. Americans from minority groups are generally willing to get the vaccine, but it is typically much less available to them. Vaccine hesitancy is higher in white populations, as it was before the current pandemic. On the other hand, many Native American communities are having outstanding success in vaccinating against COVID-19.

Resistance to vaccines draws on some deeply held American values, such as personal autonomy and the right to make individual decisions about one’s body. But history also shows that while individualism is a powerful current in our culture, its strength varies over time. Some previous eras in U.S. history showed more receptivity to public health measures that required widespread cooperation. Earlier vaccine campaigns would not have worked otherwise.

And they did work. We can trace declines in sickness and death from specific diseases after the vaccines were used. Smallpox, which killed millions of people for centuries, was the first disease to have a vaccine, although variolation, a related method of protection against the disease, was widely practiced in Asia and Africa before it was adopted in Europe and North American white settler populations. The vaccine’s inventor, Edward Jenner, rashly predicted the disease would someday be wiped out. Almost 200 years later, through a massive effort of tracing the spread, isolating the sick, and delivering the smallpox vaccine, Jenner’s prediction came true.

Smallpox eradication was partly due to scientific advances. But it was a social achievement as much as a technical one. Cooperation among numerous people and countries made it possible. Vaccine nationalism makes no sense, because microbes do not know borders.

The biggest lesson of history for vaccination may be that its success requires us to value both our personal health, and the health of others. We should value other people’s health out of social solidarity but also because our own health depends on it. No one’s safety from germs is secured at the cost of others.