Will Bondurant decided to get tested for COVID-19 after attending three racial justice demonstrations over a five-day period in San Francisco, where he lives.

The first, on June 3, “was the scariest and most risky from the point of view of COVID infection,” said Bondurant, 31. Although most wore masks, participants were jammed in, unable at times to maintain the recommended 6-foot distance, he said.

Bondurant did not have any COVID symptoms but went for the test because he had a meeting scheduled the following weekend with a friend in his late 70s.

As protests continue to ripple across the country nearly a month after Minneapolis resident George Floyd died under a policeman’s knee, political leaders and public health experts warn that mass gatherings — including the indoor Tulsa, Oklahoma, campaign rally President Donald Trump held Saturday — will further fuel new coronavirus cases.

Robert Redfield, director of the Centers for Disease Control and Prevention, told members of Congress earlier this month that those who have participated in the protests should “highly consider” getting a diagnostic test for COVID-19. New York Gov. Andrew Cuomo said it was their “civic duty” to do so.

The challenge is to get tested in a way that will yield useful information.

If you have symptoms of COVID-19, such as a fever, cough, sore throat or difficulty breathing, you should seek testing immediately, health care professionals say. If you have no symptoms, here are guideposts for testing:

Timing

Experts disagree on how long to wait post-exposure before being tested: Some say at least three or four days, others say at least seven. The longer you wait, the greater the chance a test will detect any virus. But you need to weigh that against the risk of exposing others if you are infected.

Keep in mind that a test is relevant only for the day you take it. If you plan to attend more protests, you may need to be tested again — and again. And if you’re tested too early in the course of infection, the test might not detect it.

That could give false reassurance since the virus can take up to 14 days to incubate, said Dr. Ravi Kavasery, a medical director at AltaMed Health Services, a large chain of community clinics in California.

Bradley Pollock, associate dean for public health sciences at the UC Davis School of Medicine, belongs to a group of University of California health experts that had initially recommended protesters get a test three to seven days after a protest, but he now suggests waiting at least seven days.

It can take up to three days to receive test results.

How Great Was Your Risk?

“Any large gathering creates risk for transmission,” said Anne Rimoin, a professor of epidemiology at UCLA’s Fielding School of Public Health. “It’s just common sense that when you have events where people are shouting or singing or chanting and in close proximity to each other, that is the perfect storm.”

Indoor gatherings are generally considered far riskier than outdoor ones. To assess the seriousness of your exposure risk, Dr. William Miller, a professor of epidemiology at Ohio State University, suggests you consider:

• Was it difficult to maintain social distancing?
• Were people near you not wearing a mask, or coughing, shouting, or singing? Many people, or just one?
• Do you live in an area with a large number of new COVID-19 cases every day, or where the daily number is increasing?

“If your answers to those questions are yes, the risk is greater — and so is the benefit of being tested,” Miller said.

Public health experts say the risk is even higher if you were in a crowd where police sprayed tear gas, which makes people cough and rub their eyes — both potentially perilous in the era of COVID-19.

Greater Test Availability

If you decide to get tested, the availability of test sites varies widely by region. Most community health centers now offer testing, as do large urgent care centers and a growing number of CVS and Walgreens pharmacies. Google will show a list of testing sites in your area if you type in “COVID tests near me.” Remember that you want a COVID virus test — not an antibody test, which is designed to detect past infection.

Some sites may require a prescription for the test, or restrict testing to people with symptoms and workers deemed essential. In some jurisdictions, including California’s Los Angeles, Riverside and Santa Clara counties, testing is available free to all residents, symptomatic or not.

Several U.S. cities, including Boston, San Francisco, Atlanta, Seattle and Louisville, Kentucky, have offered free COVID-19 tests to people who say they participated in the protests.

Federal law requires all insurers to cover the entire cost of testing for the virus, regardless of symptoms and when or where a possible infection may have been acquired. However, some health plans require that the test be ordered by a doctor.

There is also the option of using one of several FDA-authorized home tests, including ones from LabCorp, EverlyWell Inc. and Phosphorus Diagnostics. They cost from $75 to $150, and results are typically posted online within three days.

Medicare covers their cost, as do private insurers, although, again, the private health plans may require a referral from a health provider.

People who are uninsured can get cost-free COVID testing through Medicaid in 21 states, and a separate federal program reimburses medical providers for the cost of testing the uninsured.

Accuracy Has Improved

FDA-validated home tests have accuracy percentage rates “in the high 90s,” said Mark Cameron, an immunologist and an associate professor at the Case Western Reserve University School of Medicine in Cleveland. But since the tests are new and were approved on an emergency basis, take any result with a grain of salt, he suggested.

The “nasopharyngeal” test, in which a medical professional slides a long swab to the back of your nasal cavity, is considered by many public health experts to be the gold standard. Less invasive options include oral swabs, shallower nasal swabs and, more recently, a saliva test.

“Oral swabs are probably not as good as nasopharyngeal swabs, but they may be good enough,” said Pollock.

Several factors can cause a test to inaccurately miss an infection, including human error in collecting the sample and a low viral load in the swabbed area.

The most important factor might be the timing of the test.

Bondurant, the San Francisco resident, struggled with that calculation, because he needed the result before he visited his elder friend.

He decided to take the test on June 9, six days after the first protest he attended. The result came back the very next day — negative, he said.

But UCLA’s Rimoin counsels caution on interpreting a test that shows no infection. “A negative test a week after being exposed certainly reduces the likelihood that somebody is infected, but it certainly does not eliminate that possibility completely,” she said.

That’s why many public health experts recommend that, regardless of testing, you limit interactions with others for 14 days after potential exposure to the virus.

“Any opportunity for spread in uninfected populations, this virus will take it,” Rimoin said. “The thing people need to remember is that we may be really tired of this virus, but this virus is nowhere near tired of us.”