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1 in 5 people tested in New York City had antibodies for the coronavirus

New York City.
(Image: © Shutterstock)

Editor’s Note: Additional testing found that 24.7% of people in New York City had tested positive for coronavirus antibodies, Governor Andrew Cuomo announced on Monday (April 27). In Westchester/Rockland, 15.1% people tested positive; in Long Island 14.4% tested positive; and in the rest of the state 3.2% tested positive. The state has conducted 7,500 tests so far. In total, 14.9% of people statewide tested positive for coronavirus antibodies.

Nearly 1 in 7 people in New York who were randomly tested  for coronavirus antibodies turned out to have them, Governor Andrew Cuomo announced today (April 23). In New York City, the number is even higher: About 1 in 5 people tested positive for antibodies to SARS-CoV-2. 

If those early results translate to the rest of the New York population, that would mean about 2.7 million people across the state would have been infected.

The antibodies suggest these people were exposed at one point to the coronavirus and recovered, Cuomo said. However, it is still not known whether or not these people  are now immune to it.

New York began a statewide antibody study on Monday (April 20) and has collected around 3,000 samples from 40 locations in 19 counties across the state so far. In New York City, around 21% of randomly sampled people had antibodies against the coronavirus; on Long Island, about 16.7% had antibodies; in Westchester and Rockland around 11.7% had antibodies; and in the rest of the state 3.6% had antibodies, Cuomo said.

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These tests were conducted over a two-day period at grocery stores and other big box stores. "The sample was by definition people who were outside the home," Cuomo said. "So we have to analyze that, what does that do to the numbers." These weren't people who were home, isolated or quarantined, Cuomo said. "What does that mean, I don't know. "People who tend to stay home likely have lower rates of infection, he added. 

If the actual infection rate among the entire population is similar to the early sample infection rate they found of 13.9%, it would change the death rate of the state, Cuomo said. New York is reporting 15,500 COVID-19 deaths, and if 2.7 million people were infected, that would mean the death rate would be 0.5%, Cuomo said.

However, that comes with "two big caveats," he said. This data is preliminary and is only a sample of 3,000 people. In addition, the state doesn't count people who died at home — not in a nursing home or hospital — or who were never tested for COVID-19, in their official tally of COVID-19 fatalities.

The state will continue testing to understand if these preliminary results hold true for a larger subset of the population. 

Similar antibody testing in Santa Clara County found that between 2.5% and 4.2% of people in the county may have been exposed, which is 50 to 85 times greater than the number of cases being reported at the time, according to a previous Live Science report. Similarly, tests in Los Angeles found that up to 5.6% of people may have been infected with the coronavirus, according to the county's Health Department. But experts previously told Live Science that those numbers are likely to be too high, because the antibody tests used in these surveys had a high false-positive rate, making their prevalence estimates likely very uncertain.

Originally published on Live Science

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  • Wanda
    admin said:
    It's not yet clear if those people are now immune to the virus.

    1 in 5 people tested in New York City had antibodies for the coronavirus : Read more
    So probably 20% of those tested were infected. Immunity aside, do we know how many of those NOT tested have been infected? Are they toughing it out at home? Are they dying in the streets or with erroneous diagnoses? Are only the symptomatic still being tested? Are those tested a representative sample? -- e.g., does their plucky appearance at grocery stores and willingness to be tested perhaps indicate that they are LESS likely to come up positive than the population as a whole? I am not a scientist. I definitely am not a statistician. I'm just an old retiree trying to make sense of the data, recommendations, and numbers that are coming at us. I'm not part of the problem (I've been in isolation since Day One in CA); I just want to be part of the solution by requesting explanations for us in the masses in words of one or two syllables.
    Reply
  • tortadon
    Also not A knowledge giant but I am older and my past seems to make me think of life when Measles and Mumps was just A great way to get out of school as A 3rd grader. My point is this, we all were in the same classrooms so we were all exposed yet only A few actually got the cool bumps and swollen cheeks while the rest went on with school.
    This virus we get some of us and others will never know they had it.If Trump had not acted when he did it would have probably been nasty. His actions bought us time to let those with the skills to prepare and while we will be damaged in our billfolds our lives will probably adjust and move on.
    Reply
  • Eschand
    Wanda said:
    So probably 20% of those tested were infected. Immunity aside, do we know how many of those NOT tested have been infected? Are they toughing it out at home? Are they dying in the streets or with erroneous diagnoses? Are only the symptomatic still being tested? Are those tested a representative sample? -- e.g., does their plucky appearance at grocery stores and willingness to be tested perhaps indicate that they are LESS likely to come up positive than the population as a whole? I am not a scientist. I definitely am not a statistician. I'm just an old retiree trying to make sense of the data, recommendations, and numbers that are coming at us. I'm not part of the problem (I've been in isolation since Day One in CA); I just want to be part of the solution by requesting explanations for us in the masses in words of one or two syllables.

    Wanda,

    The idea of random sampling or testing is to capture the most diverse subset of people possible. This should, if done correctly, mean that the subset very closely resembles the general population not being tested. With this said we should be able to extrapolate that up to 20% or those living in NYC have had the virus and recovered. Now as for toughing it out or misdiagnosis, I doubt that either of these things are happening with any regularity. There is a ton of evidence coming in that points to infection without symptoms, or with extremely minor nearly unnoticeable symptoms, so that I suspect a great majority of these people never even knew they had the virus in the first place.

    Bottom line, between 50 and 85 people have the virus and never know it for every one that has it bad enough to seek treatment. The reason the governor brings up not knowing if the antibodies stop a person from reinfection is because people like me are watching the antibody statistics very intently. Antibodies are our safeguard against this thing so if they do what they are supposed to, stop reinfection, we are a quarter of the way to herd immunity (the virus can't spread because people who are introduced to the virus destroy it with their immune response and thus fail to pass it to someone else. We are essentially 1/4 of the way to this thing running its course without a vaccination. And with the exponential growth rate, even slowed with precautions, In my opinion that means we are a few short months from getting things back to normal.
    Reply