Will Compernolle spent an hour waiting on line for an antibody test outside the MedRite Urgent Care in Clinton Hill on Thursday, hoping to get some closure. He had recently recovered from a prolonged bout of fatigue and a lost sense of taste and smell that his doctor had diagnosed via video appointment as COVID-19.

“If I got confirmation, I would still proceed cautiously with my life, but would be a little more confident about marginal decisions like when to go to the grocery store or see my girlfriend,” said Compernolle, an economist who lives in Brooklyn. “I knew there was some uncertainty about the accuracy of the test and how long antibodies last, but I feel like I’m in limbo and want to know whether I had it or not.”

But after getting blood drawn for the antibody test—and handing over a $50 copay—Compernolle saw an alert that’s been circulating from the city Health Department. What little assurance Compernolle was hoping to receive from the test results seemed to evaporate.

There was a line around the block at the urgent care facility I went to yesterday for anti-body tests. Apparently it was a waste of time for everyone? https://t.co/Hd8TdhjjHM — Will Compernolle (@UpsetPatterns) April 24, 2020

The alert, which was sent to New York doctors earlier this week, said antibody tests should not be used to diagnose prior coronavirus infections or to determine whether someone is immune to the disease.

“They may produce false negative or false positive results, the consequences of which include providing patients incorrect guidance on preventive interventions like physical distancing or protective equipment,” cautioned Dr. Demetre Daskalakis, deputy commissioner of the City Health Department’s Division of Disease Control.

At a press conference on Friday, Mayor Bill de Blasio affirmed the message.

“We want to always be really up front with anyone who would get antibody testing that it is not a guarantee, it's not a rock solid guarantee, even if you test positive, that yes, you've been exposed to this virus,” de Blasio said. “It doesn't 100 percent guarantee you can't get it again.”

“If the test I just took is unreliable, then what is the point?” wondered Compernolle. “I honestly don’t know why this urgent care was offering tests. What can anyone deduce from it?”

City officials have started to emphasize that individual antibody test results have limited utility for personal decision-making just as testing sites are popping up at doctor’s offices, urgent care centers and hospitals across the five boroughs—as well as at grocery stores, where the state is conducting antibody tests of its own. Governor Andrew Cuomo has said he hopes to conduct widespread antibody testing to help generate more data about the spread of the disease in different communities.

The FDA has so far granted emergency use authorization to only a small handful of the tests on the market, including the one developed at Mount Sinai Health System, but is allowing others to be offered as they are reviewed. Among the tests available, accuracy varies widely.

Despite the cloud of uncertainty hanging over the tests, city officials haven’t cautioned against getting them, sought to direct people towards testing sites that are more reliable, or said anything about sanctioning medical practices that make misleading claims.

“I’m certainly worried that people will get a positive antibody test and feel they have some superpower or armor and no longer take precautions about covering their face in public or limiting contact with people who are vulnerable,” said City Councilmember Mark Levine. “That would really be unwise.”

Still, like de Blasio, he said he understood the value of testing for developing data about infection rates among the population as a whole, and for identifying people who can donate blood that can be used in experimental treatments for people who are currently infected with the virus.

Listen to Fred Mogul's report on antibody testing on WNYC:

For people who are being forced to quickly return to work outside their homes after being sick, antibody testing might at least be able to offer some information and peace of mind, says Dr. Ramon Tallaj, founder and chairman of the board of Somos Community Care. The network of nearly 2,500 doctors serving low-income patients across the city has tested about 1,000 people for antibodies since it launched the initiative a couple of weeks ago and is expanding to new testing sites.

One of the tests Somos is using comes from a Georgia company, RayBiotech, which initially said its test was 85 percent accurate but later claimed 90 to 92 percent accuracy after subsequent testing. It is still awaiting FDA review of its application for emergency use authorization.

“We have to keep helping our people,” said Tallaj. “While there’s no panacea, any answer now is better than going to work without knowing anything.”

Unlike some testing sites, which are charging people out-of-pocket for antibody tests, Tallaj said his organization is offering them to patients for free and has spent upwards of $7 million on the initiative so far.

He called the current tests that are available the “JC Penney” of tests. “Maybe tomorrow someone will come out with the Neiman Marcus test, and if we have it, I hope to see the Neiman Marcus test come to the people who need it the most,” he said.

Tallaj said doctors at Somos offer patients a disclaimer about the tests when they get them.

Despite all the caveats and uncertainty, many New Yorkers still have a strong impulse to get tested.

David, a paralegal from Crown Heights who went to get tested at the Clinton Hill MedRite on Friday, says he suspects he had a mild form of the coronavirus in March.

“I’ve read the news that nobody knows for sure that there’s immunity or that it’s long-lasting, so I’m not really sure it will make me feel that much more secure,” said David, who declined to give his last name. But he said he believes a positive test result might come in handy in the future.

“When it comes time to go back to work, I have a feeling that people who can prove that they've already had it will somehow get preferential treatment to be able to go and move around, and I’m hoping that this will help,” he said.

Compernolle said MedRite provided little information about the test when he went in to get his finger pricked, which took about five minutes.

“When the nurse was filling out the paperwork, I asked some questions and she shook her head like, ‘I don’t know,’” said Compernolle. “Luckily, they weren’t overpromising anything,” either.

By contrast, the state Department of Health offered a handout with answers to a long list of questions at the testing site it set up at a C-Town in Park Slope Friday. The handout explained how antibodies work, when they can be detected, and the likelihood that a test will trigger a false positive by registering antibodies that someone has developed in response to a different respiratory disease (the state test is “93 to 100%” accurate, the handout said).

The handout also addressed the question of whether a positive test result indicates immunity.

“This won’t be known until people who have [antibodies] are exposed again to [the novel coronavirus] and we can study whether any of them are infected again,” it said, adding that it’s also unclear how long the antibodies last.

“In the meantime, this test is the best we can do to indicate some sort of immunity,” the FAQ concluded.

Angela Chiarelli, 63, went to C-Town to get the test Friday after hearing about the pop-up on the Nextdoor app. Chiarelli is a patient access representative at Kingsbrook Jewish Medical Center and said she waited over an hour for the test, “so I don’t have to be nervous going back to work.”

For some on line to get tested, it was hard not to get their hopes up about the results they would receive in the next 72 hours.

“I’m curious and, of course, I’m hoping I had it and I’m past it and maybe I can go back to some sense of normalcy,” said Ari Benami, 56. He added that he also hoped to contribute to the statistics about the virus, “so, generally, we will know what’s going on.”

“The more tests we do, I guess the smarter we are about this,” Benami said, “and hopefully we can get out of the lockdown soon.”