New York City remains under seemingly interminable pandemic lockdown. But as researchers around the globe chase the promise of antibody tests—which have faced criticism for their mixed accuracy and dubious reputation as harbingers of COVID-19-immunity—a new wave of such testing in America’s largest city offered a glimmer of hope.
Mayor Bill de Blasio on Thursday detailed a plan to ramp up antibody testing locally, and specifically to survey about 140,000 people over two weeks in order to “understand COVID-19 spread and provide New Yorkers with more clarity,” as his office explained. Five testing sites will be set up in each of the five boroughs, according to the mayor, the idea being to provide free tests to 1,000 people per day by appointment through a hotline. Results from the tests will be available within 24 to 48 hours, he said.
So-called serology, or antibody, tests can determine if a person recently had the infection and may—may—have developed enough of the right kind of immune response to offer some protection from illness. De Blasio’s announcement came a few days after Gov. Andrew Cuomo detailed the results of a New York State antibody initiative that tested 15,000 people and concluded roughly one in five NYC residents had been infected.
While projects like these barely make a dent in the population of America’s number one COVID-19 hotzone, they have the potential to provide serious insight into what percentage of New Yorkers, from what neighborhoods, and in what demographics, have had the novel coronavirus, experts said. That, in turn, represents a key pillar of what epidemiologists tend to describe as a precondition for responsibly reopening hard-hit areas.
“It will give us a lot more data about the extent of spread in New York, and they may even be able to say who was most at risk, who may have already had it, how it may have spread,” said Dr. Ania Wajnberg, an associate professor in the Department of Medicine & Department of Geriatrics and Palliative Medicine at the Icahn School of Medicine at Mount Sinai.
Nearly one month ago, Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases said the American public was “days” away from rapid antibody tests for COVID-19, of which a dozen have now received emergency authorization from the FDA.
But as Dr. William Haseltine, a former Harvard Medical School professor and the president of the global health think tank ACCESS Health International, explained, there are a few issues even with some of the antibody tests that have received that preliminary OK. Some are not specific enough about what coronaviruses they pick up on. This means that even if most people who were infected developed an effective immune response to the virus, some tests might not determine if they’ve had COVID-19 or an unrelated cold.
What’s worse, tests that have not been given such authorization have dominated the market, bringing concerns about accuracy and credibility to all antibody tests, even those that can perform with excellent specificity and sensitivity.
But perhaps the main issue, according to Haseltine, is that experts are still uncertain that people who recover from COVID-19 can even create enough of the right immune response to protect them from reinfection. There simply isn’t enough data to know for sure yet.
On the first point, though, there’s growing optimism that these tests may play a part in pandemic surveillance—sooner than later.
“It really depends on which test you’re using,” said Wajnberg, who has been directing a team testing serum antibodies to identify donors for Mt. Sinai hospital’s convalescent plasma program since the pandemic began to ravage the city. The serology test Mount Sinai is using in her department has an “extremely high specificity and does not cross-react with other coronaviruses,” she said.
“It was in a research lab two months ago and we’ve moved it into the clinical setting as fast as humanly possible,” said Wajnberg, noting that it had FDA emergency use authorization. “We’re doing a couple of thousand a day.”
BioReference Laboratories, based in Elmwood Park, New Jersey, has said it is working with New York City on its antibody testing project. According to Avery Cohen, the deputy press secretary for the mayor, BioReference is using Roche’s Elecsys test for the survey, which has received FDA emergency use authorization and in a study of 5,275 samples was found to have a specificity of 99.8 percent, indicating low likelihood of false positives. The test’s sensitivity was 100 percent, according to Cohen, suggesting even higher performance at not delivering false negatives. The FDA documents provided with the emergency use authorization served to bolster those numbers. When presented with that data, Wajnberg said Roche’s test appeared to be a “reasonable test to use” for the survey’s effectiveness. Haseltine, for his part, said the Roche sensitivity and specificity numbers were “very good.”
Still, Wajnberg and Haseltine cautioned there were still too many unknowns to say for sure that someone who tested positive for antibodies—especially given the varied quality of tests—has any actual immunity. Essentially, the test might be a game-changer for data collection and knowledge about the virus, but it won’t definitively be able to tell you that you can safely return to work.
“It definitely does not mean that you are protected,” added Haseltine. “But it can give you an idea of how widely the infection has spread within the population.”
To that end, he continued, “If they really want to have an idea of how widespread the infection is, they should make every possible effort to represent every group in the city, particularly underserved minority groups. Look at people who are homeless, in jails, in eldercare homes, people who are on food stamps, to get a cross-representation of the city and map it by geographical area, then make that detailed information public.”
Ultimately, Wajnberg argued, a survey like New York City’s forthcoming one could be valuable because it might provide vital information to policymakers about how and when to open the city. For example, she said, “if this has affected 30 percent of our population, that’s very different than 1 percent. In terms of reopening, it will help modelers and epidemiologists plan better for what we can expect to see in three months or six months.”
Dr. Brittany Kmush, an assistant professor at Syracuse University who specializes in epidemiology, global health, and infectious diseases, agreed, noting that “surveys like this” are useful to knowing something even as basic as the true case fatality ratio of the virus. But that data is “population level information,” cautioned Kmush, not for making individual decisions like returning to work.
The only downside, said Haseltine, echoing many of his colleagues in recent weeks, is that a positive antibody test “may give people a false sense that they’re protected when they’re not.
“People shouldn’t feel like this makes them invincible,” added Wajnberg. “Many people who’ve tested positive here say, ‘Oh, I have superpowers!’ and I understand why they feel that way, but we need more time to really do the science behind it and make sure that people don’t have a false sense of security.”