At least 26 people were killed Sunday after a gunman opened fire on a church in a rural Texas community, in the deadliest church shooting in US history. And horrific as this event was, it was, somehow, not the deadliest mass shooting that occurred in recent weeks. On Oct. 1, a gunman killed 59 people, including himself, and injured hundreds more at a Las Vegas concert, in the deadliest overall shooting in US history.

The United States spends more on health than any other economically comparable country, yet sees a consistently mediocre return on this investment. This could be because the United States invests overwhelmingly in medicine and curative care, at the expense of the social, economic, and environmental determinants of health—factors like quality education and housing, the safety of our air and water, and the nutritional content of our food. A deeper investment in contextual factors like these can help create healthy societies and prevent disease before it occurs.

Gun violence is a public health crisis. As dean of the Boston University School of Public Health, I often comment in the wake of mass shootings. Every time, I try to find a new way of saying what we all know: that mass shootings are a uniquely American epidemic, that we could greatly reduce their number through common sense gun laws passed at the federal level, that the political inertia around this issue is literally killing people.

President Donald Trump has failed Puerto Rico. Notwithstanding his pledge to visit the U.S. commonwealth next week, a coordinated federal relief effort has been slow to coalesce, even as the situation on the ground grows more dire. Trump himself has been slow to speak as well as to act. In the days after the storm, he tweeted 17 times on the subject of football players kneeling during the national anthem to protest racism, but could not spare a single statement addressing the crisis in Puerto Rico.

On July 16, 1945, the first atomic bomb was successfully tested in Alamogordo, New Mexico. Robert Oppenheimer, the director of the Los Alamos Laboratory that developed the bomb, would later recall that, on witnessing the explosion, he found himself thinking of a line from the Bhagavad Gita: “Now I am become Death, the destroyer of worlds.” This ancient phrase is fitting when applied to the subject of nuclear weapons, a technology with the potential to end life on earth. When discussing such a terrible possibility, it makes sense that we should use only our most carefully considered words.

Once a hurricane is over, there is never a better time to forget it ever happened. For the majority of Americans who do not live in a region that has been recently devastated by a storm, this can be easy. Perhaps with the exception of Hurricane Katrina, large-scale natural disasters capture the national interest under just two circumstances: right before they occur and right after. This can be hard to accept, especially in the midst of a terrible, still-unfolding hurricane season. On the heels of Harvey and Irma, Hurricane Maria has created devastation in the Caribbean, killing at least one person and ravaging sections of Dominica. As it speeds toward Puerto Rico, the governor of the island has called it “the biggest and potentially most catastrophic hurricane to hit Puerto Rico in a century.” It is hard to imagine ever forgetting such devastation. Yet, time and again, we do. Why?

As Hurricane Harvey bore down on the United States, President Trump pledged to unleash “the full force of government” to assist the victims of the storm. The White House later released a statement outlining the administration’s plan to make federal funds available to affected individuals, state and local governments, and some nonprofit organizations to meet the demands of the emergency. In the ensuing days, as rain and floodwaters have inundated Texas, Americans have responded generously, adding to the resources available to Harvey’s victims. Celebrities and businesses have contributed millions to relief efforts, airlines have offered miles in exchange for disaster relief donations, and everyday citizens continue to give their time and money to help those whose lives were shaken by the hurricane.

The national turmoil we are witnessing [in the United States] is not just a crisis of institutions, or politics, or a society at a crossroads. It is also a crisis of health.

Hate, such as the kind we witnessed in Charlottesville, Virginia, is like a disease, spreading among populations, undermining health in a manner eerily similar to that of a pathogen. When a society is infected by hate, it is not hard to see how it can affect our bodies and minds.