At a clinic in Corona, a working-class neighborhood in Queens, more than 68 percent of people tested positive for antibodies to the new coronavirus. At another clinic in Jackson Heights, Queens, that number was 56 percent. But at a clinic in Cobble Hill, a mostly white and wealthy neighborhood in Brooklyn, only 13 percent of people tested positive for antibodies.
As it has swept through New York, the coronavirus has exposed stark inequalities in nearly every aspect of city life, from who has been most affected to how the health care system cared for those patients. Many lower-income neighborhoods, where Black and Latino residents make up a large part of the population, were hard hit, while many wealthy neighborhoods suffered much less.
But now, as the city braces for a possible second wave of the virus, some of those vulnerabilities may flip, with the affluent neighborhoods becoming most at risk of a surge. According to antibody test results from CityMD that were shared with The New York Times, some neighborhoods were so exposed to the virus during the peak of the epidemic in March and April that they might have some protection during a second wave.
“Some communities might have herd immunity,” said Dr. Daniel Frogel, a senior vice president for operations at CityMD, which plays a key role in the city’s testing program.
The CityMD statistics — which Dr. Frogel provided during an interview and which reflect tests done between late April and late June — appear to present the starkest picture yet of how infection rates have diverged across neighborhoods in the city.
As of June 26, CityMD had administered about 314,000 antibody tests in New York City. Citywide, 26 percent of the tests came back positive.
But Dr. Frogel said the testing results in Jackson Heights and Corona seemed to “jump off the map.”
While stopping short of predicting that those neighborhoods would be protected against a major new outbreak of the virus — a phenomenon known as herd immunity — several epidemiologists said that the different levels of antibody prevalence across the city are likely to play a role in what happens next, assuming that antibodies do in fact offer significant protection against future infection.
“In the future, the infection rate should really be lower in minority communities,” said Kitaw Demissie, an epidemiologist and the dean of the School of Public Health at SUNY Downstate Medical Center in Brooklyn.
Dr. Ted Long, the executive director of the city’s contact-tracing program, said that while much remained unknown about the strength and duration of the protection that antibodies offer, he was hopeful that hard-hit communities like Corona would have some degree of protection because of their high rate of positive tests. “We hope that that will confer greater herd immunity,” he said.
Neighborhoods that had relatively low infection rates — and where few residents have antibodies — are especially vulnerable going forward. There could be some degree of “catch up” among neighborhoods, said Prof. Denis Nash, an epidemiology professor at the CUNY School of Public Health.
But he added that even if infection rate were to climb in wealthier neighborhoods, “there are advantages to being in the neighborhoods that are hit later.” For one, doctors have become somewhat more adept at treating severe cases.
Some epidemiologists and virologists cautioned that not enough data exists to conclude that any areas have herd immunity. For starters, the fact that 68.4 percent of tests taken at an urgent care center in Corona came back positive does not mean that 68.4 percent of residents had been infected.
“For sure, the persons who are seeking antibody testing probably have a higher likelihood of being positive than the general population,” said Professor Nash. “If you went out in Corona and tested a representative sample, it wouldn’t be 68 percent.”
So far, the federal government has released relatively little data from antibody testing — making the CityMD data all the more striking. The Centers for Disease Control and Prevention, for instance, has published limited data that suggested that 6.93 percent of residents in New York City and part of Long Island had antibodies. But that survey was based on samples collected mainly in March, before many infected New Yorkers might have developed antibodies.
New York State conducted a more comprehensive survey on antibody rates, which involved testing some 28,419 people across the state. That survey suggested that roughly 21.6 percent of New York City residents had antibodies. But it also revealed a much higher rate in some neighborhoods. While the state has released little data from Queens, its numbers showed that in Flatbush, Brooklyn, for example, about 45 percent of those tested had antibodies.
The CityMD data provides similar conclusions. At a location in Bushwick, a Brooklyn neighborhood which has a large Hispanic population and where the median household income is below the citywide average, some 35 percent of antibody tests were positive, according to Dr. Frogel.
Dr. Frogel said that across the Bronx, which has had the city’s highest death rate from Covid-19, about 37 percent of antibody tests were turning up positive.
The CityMD in Corona, on Junction Boulevard, serves a predominantly Hispanic neighborhood whose residents include many construction workers and restaurant employees. Many had to work throughout the pandemic, raising their risk of infection.
Angela Rasmussen, a virologist at Columbia University, called the high positive rate in Corona “a stunning finding.” Epidemiologists said the rate showed the limits of New York’s strategy in curtailing the virus: While public health measures may have slowed the spread in some neighborhoods, they did far less for others.
There are reasons parts of Queens were hit so hard. Homes in Elmhurst and parts of Corona are especially crowded — the highest rate of household crowding in the city, according to census bureau data from 2014. Given that transmission among family members is a leading driver of the disease’s spread, it is unsurprising that crowded households have been associated with higher risk of infection.
For residents of Corona, the main sources of employment are jobs in hospitality, including restaurants, as well as construction and manufacturing, according to a 2019 report by the Citizens’ Committee for Children of New York. Many construction workers and restaurant employees showed up to work throughout the pandemic, elevating their risk of infection.
“Our plan did not really accommodate essential workers as it did people privileged enough — for lack of a better word — to socially distance themselves,” Professor Nash said. He said that one lesson of the past few months was that the city needed to better protect essential workers — everyone from grocery store employees to pharmacy cashiers — and make sure they had sufficient protective equipment.
Epidemiologists have estimated that at least 60 percent of a population — and perhaps as much as 80 percent — would need immunity before “herd immunity” is reached, and the virus can no longer spread widely in that community.
But scientists say it would be a mistake to base public health decisions off antibody rates across a population.
“Just looking at seroprevalence alone can’t really be used to make actionable public health decisions,” Dr. Rasmussen, the virologist at Columbia, said.
One reason is that the accuracy of the antibody tests is not fully known, nor is the extent of immunity conferred by antibodies or how long that immunity lasts. Dr. Rasmussen noted that the “magical number of 60 percent for herd immunity” assumes that everyone infected has complete protection from a second infection. “But what about people with partial protection?” she asked. “They may not get sick, but they can get infected and pass it along.”
“It is premature to discuss herd immunity, since we are still learning what the presence of Covid-19 antibodies means to an individual and whether, or for how long, that conveys immunity; and we don’t know how the level of immunity in a single community translates into herd immunity,” said Jonah Bruno, a spokesman for the state Department of Health.
He said he was unsurprised by the high rate in Corona, and senior officials with the city’s contact-tracing program and public hospital system agree. “We know this area was disproportionately affected,” said Dr. Andrew Wallach, a senior official in the city’s public hospital system, “so this just confirms what we’ve seen clinically.”