At least Emperor Nero supposedly only fiddled while Rome burned; he didn’t tell the Romans that the fire was no big deal.

President Trump squandered two precious months trying to downplay the coronavirus while attempting to talk up the stock market. We still have no idea how many Americans are infected, because the administration bungled diagnostics. As of a few days ago, South Korea had conducted up to 700 times more tests per capita than the United States.

Trump’s passivity will cost lives, but we can still make preparations before hospitals risk becoming overwhelmed by a pandemic that is both more contagious than the seasonal flu and apparently many times more lethal. Dr. Tom Frieden, a former director of the Centers for Disease Control and Prevention, warns that in a plausible worst-case scenario, this virus could kill more than one million Americans.

After speaking to epidemiologists and public health specialists, I have a list of some practical steps that the president and other officials should take immediately, while there is time.

1. Invest in a huge rollout of free testing so that we know who is sick. The University of Washington set up a drive-through system so that certain people can be tested without contaminating a clinic.

2. Cancel large gatherings in parts of the country where community transmission is occurring, as Gov. Jay Inslee has done in Washington State. Employers should encourage people to work from home where possible. Even with social distancing, more than one-third of Americans may eventually be infected (a worst case is that 70 percent become infected, as Chancellor Angela Merkel of Germany has cautioned for her country).

But lives will be saved by flattening the curve so that infections grow more slowly. We are much better off if 100 million Americans contract the coronavirus over 18 months rather than over 18 weeks, and this also gives scientists the chance to test treatments and develop vaccines, and to see if warmer weather helps. South Korea’s experience suggests that aggressive measures, well short of China’s, do help.

3. Expand telemedicine so that patients can get medical advice while staying home. The aim is for people to NOT go to a doctor’s office or E.R. unless necessary.

4. Plan for hospitals to be overwhelmed, as happened in Wuhan, China, in Iran and northern Italy. Epidemiological models suggest that by April we could have millions of Americans infected, and the danger is that people with other ailments die for want of care in the chaos. Epidemiologists suggest that we could easily see 100 million infections of the new coronavirus in the United States, of which 5 or 10 percent might require hospitalization and 1 percent might need a ventilator. That could mean almost one million people needing ventilators just for Covid-19, though not all at the same time, yet we have only about 72,000 full ventilators in the United States.

5. Cancel vacations of health workers, bring back retired doctors and nurses, and repurpose cardiologists and pediatricians to deal with a torrent of coronavirus patients — in expectation of record numbers of doctors out sick. We should prepare to allow military medics to assist in E.R.s as well.

6. Make nursing homes, assisted-living centers, homeless shelters, prisons and dialysis treatment centers safer, by encouraging use of personal protective equipment and limiting visitors.

7. Make plans in case first responders, such as firefighters and ambulance paramedics, become sick in large numbers. That may mean calling in the National Guard.

8. Ensure that as many people as possible have access to medical care. That means expanding Medicaid in remaining states, and establishing a mechanism so that no one needs to pay (including a co-pay or deductible) for testing for or treatment of Covid-19.

9. Congress should promptly pass legislation (shamefully stalled for the last 16 years) mandating paid sick leave for all workers.

10. Greatly step up production of personal protective equipment needed in hospitals. Some hospitals are already running short of N95 masks, and America’s emergency stockpile has only 12 million N95 masks — approximately a one-day supply for the country during an epidemic.

11. Prepare for public school students to attend classes remotely in parts of the country most affected. Researchers found that during the 1918 Spanish flu, cities that canceled schools and public gatherings — and did so early — fared better than other cities. Unfortunately, today at least six million American schoolchildren don’t have internet access at home; that may mean that schools hand out hotspots, and laptops to students without computers. A nonprofit called FirstBook is trying to send out six million books to low-income schools so that kids can at least read while at home.

12. Instead of bailing out airlines or cruise lines, make people in quarantine eligible for unemployment insurance and waive work requirements for benefit programs. Don’t let struggling families become homeless because they suddenly can’t make the rent or meet mortgage payments.

Enough fiddling, Mr. President. Let’s roll.

Nicholas Kristof is a columnist for the New York Times.