In order to be tested for the coronavirus, you’ve got to have symptoms of COVID-19. Demand for the PCR (polymerase chain reaction) test has exceeded the supply, forcing health care providers to limit testing. With a death rate at least 10 times the flu, concern about being infected is understandable. But testing only the sick is not the most efficient way to end the pandemic.

The vast majority of people with colds or flu-like symptoms who have the coronavirus do not progress to the severe form of the disease, characterized particularly by shortness of breath. Testing people with mild COVID-19 enables those who test positive to be isolated in order to prevent others, including immediate family, from becoming infected. That will slow the spread of the coronavirus. However, community-wide testing of everyone, healthy or sick, is a more efficient way to slow the pandemic. That is because healthy people infect others with the coronavirus.

Shortly after the first COVID-19 death in Italy occurred in Vo, the 3,000 residents were quarantined and every one of them was tested for the virus. Of the 89 (3%) who tested positive, more than half were completely free of symptoms. They were all quarantined. In a second round of testing nine days later, only six additional cases were discovered, and there were no further cases. Iceland has tested about 1% of its citizens as of March 18. About half of all people who tested positive had no symptoms. South Korea tested 0.6% of its 51 million citizens. That was enough to curb the epidemic. In the United States, the Centers for Disease Control and Prevention and public health labs have tested only 0.04 % since Jan. 18. On its peak day, March 17, they tested only 0.003% of the population. Probably, a large percentage of them were already sick.

Sheltering-in-place and social-distancing are leaky strategies. We still need farmers to produce food and a vast workforce to get it to our tables. We still need an army of health care providers and ancillary staff to treat the exponentially increasing number of COVID-19 patients. We still need factory workers to produce respirators and personal protective equipment. We still need police and firefighters. Collectively, they and other essential workers are the source of new coronavirus infections that will continue to plague the population. Another strategy is needed: case finding. If we could test the entire population, as in Vo, and quarantine everyone who tested positive, we could stop the increase in cases in a matter of weeks. If we could test 1% or 0.6%, it would take longer. But right now only sick people are being tested, and health department laboratories don’t have the per-capita testing capabilities of Iceland or South Korea.

Every year in the United States we screen over 3 million newborns to find those affected with rare diseases like PKU and congenital hypothyroidism. Most of this testing is done in health department laboratories. It’s equivalent to testing about 0.002% of the American population every day or two-thirds of current health department testing for the coronavirus. It’s not clear that Congress has allocated funds to accomplish this expansion. If it has, or will, over 16,000 healthy people could be tested nationwide each day, and between 160 and 1,600 new infected people would be found. They would represent 1.2% to 12% more than the 13,000 symptomatic cases diagnosed on the most recent day for which data are available.

The United States does not have enough health care providers to test healthy people. Commercial testing laboratories have their hands full with testing people with symptoms. Without expanding state and local health departments’ personnel and testing capacity, we are neglecting their ability to stem the epidemic.

Realistic technologic advances in PCR testing will expand the supply of tests for the virus. Drive-through and other novel services will facilitate community-wide case finding. To be sure, there are still problems. Personnel need better protection while collecting and processing specimens. Techniques for nose and throat swabs must be monitored to make sure people with the coronavirus are not being missed. Failure to do so results will result in false negative results. This is a more serious problem than mistakenly identifying healthy people as infected (false positives). Nevertheless in the vast majority of people, testing is accurate.

Our failure to initiate case finding has escalated the number of cases, overwhelmed our hospitals, and caused mass unemployment and economic depression. Relying alone on sheltering in place and safe distancing will take much longer to slow the epidemic and cost thousands of lives nationwide that need not have been lost.

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Neil A. “Tony” Holtzman, M.D., M.P.H., is a part-time resident on Upper Saranac Lake and assures the editor that he will not return to the Adirondacks until he has either survived COVID-19 or is immune to it. Right now he is sheltered at home in Menlo Park, California, and is healthy. He is emeritus professor of pediatrics at the Johns Hopkins School of Medicine. From 1978 to 1983 he was the medical director of newborn screening for the Maryland Department of Health.