Human health is collective. What happens to you will eventually affect me and my offspring.  It has always been thus.

The evidence is deep in your DNA. Large parts of our DNA come from bacteria and viruses. We have been dealing with infections as long as there has been multicellular life. That’s at least six hundred million years.

There are nearly 7.8 billion of us on the planet. A large reason we survive is our collective, herd immunity, our common resistance to infection. If enough of us have immunity, as for example to rubella, the rest receives protection.

Look at your DNA, and you will see that herd immunity has been sorely tested millions and millions of times.

Viruses can mutate in a matter of hours. Sometimes that makes them more infectious and deadly, often not. Our herd immunity sees us through.

Yet not without struggle. The written history of humanity shows many critical points of massive change caused by epidemics, often accompanied by wars. Until the twentieth century what killed most people was infections.  Eventually, as will be the case with Covid-19 when enough of us have been infected or hopefully vaccinated, our herd immunity will see us through.

We are the same species, with most of us coming from the same group that may have come close to dying out 75,000 years ago. We are a very social species. We move around. Whether it’s the first or the twenty first century, epidemics move with us.

That is something many countries figured out after World War II. They recognized their collective health was critical to their economic and political survival. Even poor nations set up public health departments, and tried to create national health systems so that everyone had some form of basic care. When the history of Covid-19 will be written, I expect that countries with nationally organized public health systems, in part because they had the data and tools to take decisive action, will be recognized as having done a far better job than those who did not.

In this game, the United States has been the giant outlier.

Maybe this time we’ll learn, that everybody else’s health is mine, and mine theirs. A healthy economy acquires a healthy population. A healthy population requires a healthy environment – including the control of infectious disease. Vaccinations are one of humanity’s great inventions.

So when you go down the street, recognize that with each breath you may expel thousands or ten of thousands of viral particles. Perhaps only a few hundred are necessary to infect anybody who comes within that stream.

Which is why physical (or social) distancing is so important. Many people with Covid-19 won’t know they have it. Your health is their health. Their health is yours.

Act in a way that’s good for both.

No matter what, herd immunity will get the species through this epidemic. It has for millions of years.

What we want is that we as individuals make it through, too.