Never let a pandemic go to waste. You might learn something.

A month ago, how much did you know about self-quarantine, social distancing, contact tracing, flattening the curve, or disease testing kits? Now, most of us know that they may save our life — and the lives of millions of others.

A month ago, could you name the director of the National Institute of Allergy and Infectious Diseases? Now, this government official, Anthony Fauci, holds the entire country’s welfare in his hands.

A month ago, did you think that hand sanitizer, rubbing alcohol, surgical masks — and toilet paper — would be among the most sought-after consumer products?

We have quickly learned a lot about an essential pillar of our country’s well-being — public health. It is more than the city official who closes a local restaurant or the announcer on a public service video who scolds us about wearing a seat belt. Like the security suite running in the background on your computer, it is the often-hidden support that responds to threats before the entire system crashes.

But if we don’t retain our newly gained knowledge, we will be no better prepared when the next threat emerges. Amnesia can kill.

Here are five key lessons from COVID-19 for all of us to bear in mind in the years ahead.

1. You never know when you, and everyone around you, will need public health.

Public health threats don’t usually announce themselves in advance, and they can worsen very quickly. The first case of COVID-19 occurred in Wuhan, China, last November. In December, hospitals there were treating dozens of cases. In January, the first cases were confirmed in the United States and several other countries. Public health infrastructure needs to be there to respond quickly. You don’t wait to buy an umbrella until after it begins to rain.

2. You don’t hear more about public health because it has been so successful.

Remember when epidemics of polio, smallpox, yellow fever, and cholera threatened whole cities? You almost certainly don’t because measures like vaccination, clean drinking water, sanitation, and pest control conquered them in this country decades ago, probably before you were born.

3. Public health is most effective when it is global.

Infectious diseases don’t stop at national borders and never have since the dawn of civilization. It is only through international cooperation that we can hope to control their spread, something that has been haphazard this time. Almost no nation on Earth has been spared from COVID-19. We rely on global monitoring to spot emerging flu strains each year so scientists can develop vaccines before they arrive. The more we cooperate globally, the better protected we are.

4. Public health transparency is crucial, and a free press is essential to providing it.

Chinese officials kept the public in the dark about COVID-19 until late January, while people moved freely in and out of Wuhan. China lacks a free press to spread the word. Had the Chinese public learned about the outbreak sooner, we might not be facing the current crisis. And transparency builds public trust, without which the current pandemic responses would not be possible.

5. Our whole economy depends on public health.

Take a look at the stock market. Need I say more?

Those who cannot remember the past are condemned to repeat it, as the saying goes. The lessons of a crisis are of little use if they are not kept in mind after it has passed. COVID-19 is showing us how important it is to keep the security suite running. Even when we don’t see it, we continually rely on public health security so that the threats we don’t yet see are more likely to stay that way.

Robert I. Field holds a joint appointment as a professor of law at the Kline School of Law and a professor of health management and policy at the Dornsife School of Public Health at Drexel University. He is an expert in public health law and policy and a member of The Inquirer’s Health Advisory Panel.