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New York Antibody Testing Shows Some 20% Had Novel Virus

Sampled randomly in supermarkets across the city, more than 1 in 5 New Yorkers tested positive for antibodies of the novel coronavirus, suggesting far greater exposure than was previously thought.

MANHATTAN (CN) — Sampled randomly in supermarkets across the city, more than 1 in 5 New Yorkers tested positive for antibodies of the novel coronavirus, suggesting far greater exposure than was previously thought. 

New York Governor Andrew Cuomo announced the findings Thursday at a press conference in Albany, unveiling preliminary antibody data gathered with a finger-prick study on 3,000 people in grocery and big-box stores across the state this week.

A whopping 21.2% of New York City shoppers were found to carry antibodies to Covid-19. The number 16.7% on Long Island, and statewide the number falls to 13.9% or 2.7 million people.

“This basically quantifies what we have been seeing anecdotally,” Cuomo said

With the official fatality count at about 15,500, the study says the death rate for the virus in New York is around 0.5%. 

Telling the public to take that figure with a grain of salt, however, Cuomo emphasized that the state’s official death toll does not include presumed Covid-19 deaths, such as those who died at home or those who were never tested. New York City, for example, reported 10,290 confirmed Covid-19 deaths and 5,121 “probable” Covid-19 deaths as of Thursday. 

Denis Nash, an epidemiologist at the City University of New York’s School of Public Health and Health Policy, said in an email Thursday it might be too soon to estimate the state’s Covid-19 fatality rate. Many of the current cases are still sick or in the hospital, he noted, and therefore there may be additional deaths among those estimated 2.7 million currently infected.

Even a seemingly small jump in the reported fatality rate — from 0.5% to 0.7% — is more than 3,000 people, Nash pointed out. 

New York City Mayor Bill de Blasio emphasized the importance of both antibody and diagnostic testing at a separate press conference Thursday.

“The coronavirus is alive and well and living in New York City,” he said, later adding, “the more testing we get, the more truth we will find … all roads lead to testing. The more you have, the more you can trace each person’s reality.” 

Those with antibodies are presumed to have some immunity from Covid-19, which could ultimately help leaders determine which social-distancing guidelines they should lift. Such serology testing, as it’s called, can also help predict the total number of infections in the United States, which is expected to be a dramatic undercount due to testing shortages. 

The New York study has some significant caveats: One of the more glaring issues is that people at home were excluded. By conducting the test at stores, the state considered people who left their homes representative of the rest of the state — an assumption that fails to consider the reality of households that designated one healthy or less vulnerable member to buy groceries and run errands.

It’s also possible people flocked in line to get a test because they thought they had been exposed or have had Covid-19 in recent months, which could bias the sample. More data on the study’s methods was not immediately available Thursday, and the Department of Health did not immediately respond to follow-up questions. 

“Yes, design loses value if people know about it,” Bethany Hedt-Gauthier, a global health and social medicine professor at Harvard, wrote on Twitter in response to discussions of the testing. 

Jonah Bruno, a spokesman for the state Department of Health, said the study was done in grocery stores to find enough adults for an adequate, representative sample. 

“Store locations were selected to maximize the chances that a racially/ethnically diverse population was reached,” Bruno said in an email Thursday. “Where possible, we worked with chains such as Wegmans and Price Chopper to simplify the store recruitment process. The objective was to recruit between 100-200 patrons per store. The sampling procedure selected was chosen to greatly expedite the survey, which is believed to be the largest conducted to date.”


The presence of antibodies in the blood indicate the body fought off the infection. As noted earlier this week by state Department of Health spokeswoman Jill Montag, the blood samples were processed with an immunoglobulin G (IgG) immunologic test by the state Department of Health’s Wadsworth Center. 

Immunoglobulin G is made as part of the body’s antibody response. It’s made over a longer period of time and tends to remain in the body for longer than antibodies like immunoglobulin M, making it a good candidate for helping determine whether a person has been exposed to Covid-19.

CUNY’s Nash had a lot of follow-up questions about the state’s testing.

“There are a lot of unknowns about the serologic testing they did,” he wrote. “What test did they use? What is the false positive rate? What is the false negative rate? There are a lot of concerns about the validity of tests for SARS/COV2 antibodies, especially in low prevalence settings.” 

The state’s study also indicated higher rates of black and Latino New Yorkers having Covid-19 antibodies: 22.1% of black residents and 22.5% of Latinos. Those groups made up 14.3% and 17.6% of the testing totals, respectively. That data tracks numbers nationwide that minority groups are more vulnerable to the virus because centuries of systemic racism and xenophobia have forced them into lower-wage jobs, food deserts and neighborhoods with worse air quality than Caucasians experience.  

Nash called the racial and ethnic disparities in the new state data “staggering” and consistent with New York City data on fatalities. 

More men than women in the New York study had Covid-19 antibodies — men made up 48% of all study participants and 15.9% tested positive, while women, making up the other 52%, had just a 12% positive rate. Global statistics indicate more men than women die of the virus, though scientists don’t yet know why. 

Antibody tests in general still carry a high level of uncertainty, The New York Times has reported. The Food and Drug Administration rushed approvals and the tests can be misused or be of “dubious” quality and produce dangerous false-positives or false-negative results. 

Mount Sinai microbiology professor Florian Krammer tweeted skepticism of New York’s study Thursday, saying he thought the infection rate it determined was too high. Krammer did not immediately respond to tweeted or emailed requests to expand on his views. 

“I think this is too high. It is possible. But a 20% plus infection rate seems too high for NYC due to a number of reasons. I would think 6-8%, maybe 10% are closer to the truth. It would be nice to know more about the test, its sensitivity and specificity and the test population,” he wrote. 

Mount Sinai has developed its own serology test to detect Covid-19 antibodies, and it was granted emergency-use authorization by the Food and Drug Administration earlier this month. 

In his presser Thursday, Cuomo, a Democrat, also unleashed criticism on Senate Majority Leader Mitch McConnell, who suggested the previous afternoon that states seeking more federal aid should instead declare bankruptcy. 

“This is one of the really dumb ideas of all time,” Cuomo said of McConnell’s bankruptcy comments. “Not to fund state and local governments is incredibly shortsighted. … How do you not fund police and fire and teachers and schools in the midst of this crisis?”  

Cuomo also noted that New York state, an economic engine of the country, contributes $116 billion more to the federal budget than it receives back, while Kentucky, McConnell’s state, takes more money from the feds than it puts in. 

The governor also skewered McConnell for politicizing Covid-19 relief as a “blue-state” bailout because many states hit hardest by the virus — New York, California, Washington, and Michigan — tend to vote Democratic. 

“If there were ever a time to stop your obsessive political bias and anger … now is the time,” Cuomo said. “You want to politically divide this nation now? With all that’s going on? How irresponsible, and how reckless.” 

Categories / Health, Politics, Regional, Science

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