Covid-19 evidence is sparse. Still need to get one?

What is a conscientious person who already wears a mask and maintains social distance?

Yes, said R. Alta Charo, professor of law and bioethics at the University of Wisconsin-Madison.

“One of the most important things to keep in mind when talking about public health is the fact that this is fundamentally a community problem, not simply an individual health problem,” he said. “We are all in this together. What I do affects everyone around me, and what they do affects me.”

If public health experts want people to be tested, they must comply, especially if the goal is to gather critical information about how many people are infected at any given time, Professor Charo said.

Epidemiologists can use the data to determine how fast the virus is spreading and what measures are working, he said.

Doing a test, like wearing a mask, shows “a desire to be part of the solution,” said Dr. KC Rondello, an epidemiologist at Adelphi University in Garden City, New York.

The virus has been difficult to control largely because many infected people without symptoms have spread it without knowing it, he said.

More tests will help identify these hidden cases, said Dr. Rondello.

But Candace L. Upton, a professor of philosophy at the University of Denver, said people shouldn’t feel compelled to take a test. You can even argue that it is morally wrong to undergo a test if you don’t have symptoms and are not at high risk, she said.

“Until there is no longer a shortage of test kits, it is morally unwarranted to screen patients for Covid-19 solely for the purpose of collecting data,” said Professor Upton. “Because of the deficit, labs shouldn’t offer them to people who are just curious.”

The priority should remain testing only those with symptoms or compromised immune systems, and essential workers and the elderly, he said.

Professor Upton added that tests should be done selectively even in places where tests are available and where results can be delivered quickly.

“The whole system is unfair,” he said. “And taking advantage of surpluses in certain places in the market is adding to the injustice of people who were unavailable in the first place.”

The national failure to coordinate testing efforts should not cause symptom-free people to feel conflicted when testing for the coronavirus, said Dr. Andrew Diamond, medical director of One Medical in San Francisco, a primary care practice based in membership with offices around the country.

“If there is a way to get tested that doesn’t clearly and directly affect someone who is a priority, then you should be tested safely,” he said.

24-year-old Molly Wallace, who grew up on Martha’s Vineyard, was examined after she returned to the island from Boston in March.

She was fired from her job as a medical assistant and began volunteering at a test site, Test MV, at Martha’s Vineyard Regional High School, where she went to school.

Ms. Wallace said that she had never had coronavirus symptoms but still felt compelled to be tested. “I don’t want to be the person to bring Covid here,” he said.

All island residents and visitors are encouraged to get tested at Test MV, where volunteers distribute free self-administered nasal swab kits, said Wallace, who is now the site outreach coordinator.

People generally get their results within 72 hours, or faster if they test positive for the virus, Wallace said. That’s a stark contrast to states like New York and Arizona, where the lines for testing have sometimes been stretched around blocks and the response time for results has been days, if not weeks.

The use of a mask should be mandatory, Dr. Diamond said, but should not be tested.

If tests were widely available and response times for results were much faster, people would have a greater sense of obligation to get tested, he said.

“In the current circumstances, I would say that it is much more important to continue doing what you are doing,” said Dr. Diamond. That is, wear a mask, stay six feet away from people, and stay home as much as possible, he said.

Dr. Diamond added: “Behavior is really what is going to make the biggest difference.”

Remy Tumin contributed reporting.