Think of the health care system capacity as a subway car that can only hold so many people at once. During rush hour, that capacity is not enough to handle the demand, so people must wait on the platform for their turn to ride. Staggering work hours diminishes the rush hour and increases the likelihood that you will get on the train and maybe even get a seat. Avoiding a surge of coronavirus cases can ensure that anyone who needs care will find it at the hospital.

What sorts of mitigation measures help transform the red curve into the blue curve?

Diseases spread when one person gives it to one or more others, who go on to give it to more people, and so on. How fast this occurs depends on many factors, including how contagious the disease is, how many people are vulnerable and how quickly they get sick.

The difference between seasonal flu and coronavirus is that many people have full or partial immunity to the flu virus because they have had it before or were vaccinated against it. Far more people are vulnerable to coronavirus, so it has many more targets of opportunity to spread. Keeping people apart in time and space with social distancing measures, self-isolation and actual quarantine decreases opportunities for transmission.

To take the subway example again, a packed car — or a packed subway platform — is a great place to spread the virus. But reducing the number of people on the train or platform, by asking people to work from home or to stagger their working hours, enables individuals to stay farther apart, limiting the spread of the virus. That is social distancing in action.

Mitigation efforts keep people farther apart, making every transmission opportunity marginally less likely. This slows the spread. We should, and will, take the most vulnerable people out of the population altogether by keeping them totally separate. This is what Washington State is trying to do by limiting visitors to nursing homes. Think of this as a reverse quarantine.

What are you doing day-to-day in response to these unusual times?

Like most everyone else, I’m more aware of my surroundings and behaviors. I try to use a sleeve or elbow to open doors, and I wash my hands or use hand sanitizers after I touch a surface that might be contaminated. And I made sure to have a good supply of my prescription and nonprescription medications, just in case any shortages occur after the shutdown of Chinese pharmaceutical suppliers. I’m following the lead of my public health officials here in Philadelphia, where there is only one case as of Tuesday, and travel isn’t restricted. I’m avoiding crowds and sick people. I am going out, and will continue to do so unless a quarantine is ordered or public places are closed.

I know there is a good chance that I will catch the virus before a vaccine becomes available, but I also believe I’m very likely to do fine. I’m not in any high-risk group. But I worry about the more vulnerable folks and want to do what I can to prevent the spread. I also worry about people who lack the resources I have. What happens to the self-employed, hourly workers and people in the gig economy when business stops? What about the homeless who depend upon charity and services for support? It’s these second-order effects that could be just as devastating if this epidemic really takes off.