An excerpt from Pandemics, Poverty, and Politics: Decoding the Social and Political Drivers of Pandemics from Plague to COVID-19.

We talk about health as if it were an individual act of will, a matter of personal choice or risk tolerance. But anyone who has walked alongside people living in poverty, in refugee settlements, in overcrowded housing, or on the street knows that illness does not take root in a vacuum. It grows out of systems (economic, political, and environmental) that determine who has clean water, stable housing, nutritious food, and access to care. These are the social and political determinants of health, and ignoring them all but guarantees that we will continue to spend more money to achieve worse outcomes than any other wealthy nation.

In more than two decades of practicing medicine and public health across the world, from pediatric malnutrition wards in South Sudan to street medicine in Skid Row, I have learned that the greatest barrier to health is not the absence of innovation. It is the separation of things that were never meant to be divided. In the U.S., the gap between public health and primary care has become so wide that entire communities fall through it. And the people who fall first are always those with the least power and the least trust in the systems that are supposed to protect them.

Primary care is supposed to be the first line of defense. Public health is supposed to shield entire populations. But in the U.S., these forces operate in separate orbits, connected only in moments of crisis. We wait for emergencies (a disease outbreak, a natural disaster, or a rising body count) to build the bridges that should exist every day.

During COVID-19, this fragmentation became unmistakable. In Northern California, where I led vaccination operations, early data showed that more than 90 percent of doses were going to what we called the “Triple C” or “Caucasians with cars and computers.” Meanwhile, the people most likely to die (Latinx families in crowded housing, essential workers without paid leave, unhoused neighbors on the street) were the last to be reached. The problem was not that public health lacked compassion or skill. It was that public health lacked a bridge to the reality of people’s daily lives.

That is the role primary care should play. Yet primary care itself is inaccessible for millions. And even where it exists, it often has little connection to population-level data, disease prevention frameworks, or the community trust that public health depends upon.

At Wellness Equity Alliance, the organization I lead, we are working to close this divide by refusing to separate clinical medicine from the social realities that shape health. Our mobile and street-based clinical teams bring care directly into encampments, colonias, tribal territories, migrant neighborhoods, and schools. We do this not because mobile care is novel, but because it is the only model that reliably reaches people who have been structurally excluded from health systems built for someone else.

On the streets of Los Angeles, I have cared for people who visit emergency departments more than 500 times a year. These individuals are not hard to reach. They are systemically unreached. When we bring primary care clinicians, community health workers, harm reduction specialists, and public health practitioners into the same mobile team, those same individuals stabilize. They get medications. They build trust. They return. They live. This is not charity. It is systems repair.

And it works because it treats people with dignity. In South Sudan, where I was the only physician responsible for more than 29,000 displaced people, our measles vaccination campaign succeeded only because we partnered with community health workers who held the trust we could not assume. The same dynamic holds in California, New Mexico, and every American city confronting rising chronic disease, homelessness, and addiction. Without trust, there is no health system. Without integration, there is no equity.

Integrating public health and primary care is not complicated. It requires three commitments:

• Bring care to people, not people to care. Mobile, school-based, and street-based clinical models must be funded as core health infrastructure, not temporary projects.
• Treat community health workers as essential providers. They are the bridge between systems and lived experience, between institutions and trust.
• Align incentives with outcomes, not volume. Our current model rewards sickness, not prevention. An equitable system rewards the avoidance of disease, not the treatment of its complications.

We know that integration works. We have seen it in refugee camps, in tribal nations, in the hardest-hit neighborhoods of the pandemic, and in the communities we serve every day. The question is not whether we can build the bridge. It is whether we have the courage to stop pretending the gap is someone else’s problem.

Health equity is not achieved in emergency rooms or political chambers. It is achieved in the spaces where public health meets primary care: on sidewalks, in shelters, in classrooms, in homes, and in communities that have waited far too long to be seen.

And if we fail to build that bridge now, the next pandemic will not ask us twice.

Tyler B. Evans is an infectious disease physician and author of Pandemics, Poverty, and Politics: Decoding the Social and Political Drivers of Pandemics from Plague to COVID-19.