Editor’s note: Jonathan Smith originally wrote this piece as a letter to his local neighborhood of about 50 families. It struck a chord, and his neighbors began sharing it widely within their own networks. Shortly after, and many forwards later, it has been widely distributed and treasured by many. The piece appears here at metropole.at with his direct permission. Prof. Smith is a lecturer in epidemiology at Yale University, New Haven, Conn. while completing a PhD at Emory University.

As an infectious disease epidemiologist (albeit a junior one), I feel morally obligated to provide information on what we are seeing from a transmission dynamic perspective and how it applies to the social distancing measures.

Like any good scientist, I have noticed two things that are either not well articulated or not present in the “literature” of online media. I have also relied on other infectious disease epidemiologists for peer review of this piece.

Specifically, I want to make two aspects of these distancing measures very clear and unambiguous. First, we are in the very infancy of this epidemic’s trajectory. That means that even with these measures in place, we will see cases and deaths continue to rise globally, nationally, and in our own communities.

This may lead some to think that the social distancing measures are not working. They are.

They may feel futile. They aren’t.

You will feel discouraged. You should.

This is normal in chaos. This is the normal epidemic trajectory. Stay calm.

The enemy we are facing is very good at what it does; we are not failing. We need everyone to hold the line as the epidemic inevitably gets worse.

This is not an opinion. This is the unforgiving math of epidemics for which I and my colleagues have dedicated our lives to understanding with great nuance, and this disease is no exception.

Stay strong and in solidarity knowing that what you are doing is saving lives, even as people continue getting sick and dying.

You may feel like giving in. Don’t.

You should perceive your entire family to function as a single individual unit: if one person puts themselves at risk, everyone in the unit is at risk.

Second, although social distancing measures have been (at least temporarily) well received, there is an obvious-but-overlooked phenomenon when considering groups (i.e. households) in transmission dynamics.

While social distancing decreases contact with members of society, it of course increases contact within a group (i.e. family).

This small and obvious fact has surprisingly profound implications on disease transmission dynamics.

The basic mechanics of this mathematical principle dictate that even if there is only a little bit of additional connection between groups (i.e. social dinners, playdates, unnecessary trips to the store, etc.), the epidemic likely won’t be much different than if there was no measure in place.

The same underlying fundamentals of disease transmission apply, and the result is that the community is left with all of the social and economic disruption but very little public health benefit.

You should perceive your entire family to function as a single individual unit: If one person puts themselves at risk, everyone in the unit is at risk.

Seemingly small social chains get large and complex with alarming speed.

If your son visits his girlfriend, and you later sneak over for coffee with a neighbor, your neighbor is now connected to the infected office worker that your son’s girlfriend’s mother shook hands with.

This sounds silly, it’s not.

This is not a joke or hypothetical.

We as epidemiologists see it borne out in the data time and time again. Conversely, any break in that chain breaks disease transmission along that chain.

In contrast to hand-washing and other personal measures, social distancing measures are not about individuals, they are about societies working in unison. These measures also require sustained action before results are evident.

It is hard (even for me) to conceptualize how on a population level “one quick little get together” can undermine the entire framework of a public health intervention, but it can.

I promise you it can. I promise. I promise. I promise. You can’t cheat it. People are already itching to cheat on the social distancing precautions just a “little”- a short playdate, a quick haircut, or picking up a needless item from the store.

From a transmission dynamics standpoint, this very quickly recreates a highly connected social network that undermines much of the good work our communities have done thus far.

This outbreak will not be overcome in one grand, sweeping gesture, but rather by the collection of individual choices we make in the coming months. This virus is unforgiving to unwise choices.

As this epidemic continues, it will be easy to be drawn to the idea that what we are doing isn’t working and we may feel compelled to “cheat” with unnecessary breaches of social distancing measures.

By knowing what to expect, and knowing the critical importance of maintaining these measures, my hope is to encourage continued community spirit and strategizing to persevere in this time of uncertainty.

Jonathan Smith Epidemiologist, Yale University

Jonathan Smith, an award-winning lecturer in Epidemiology of Microbial Diseases and Global Health at Yale University School of Public Health. His research focuses on infectious disease transmission dynamics and he is an affiliate of the Yale Global Health Leadership Institute and founding director of Visual Epidemiology, a non-profit organization seeking to combine academic discourse with personal narratives through filmmaking.