Antibody Tests Positive For 13 Percent On Upper East Side: Data

UPPER EAST SIDE, NY — About 13 percent of residents on the Upper East Side tested for antibodies showed signs that they were previously infected with the coronavirus that causes COVID-19, according to new city data.

Of the 57,828 residents tested in the five ZIP codes that make up the neighborhood, roughly 13.2 percent tested positive, according to data released by the Department of Health on Tuesday.

The ZIP code with the highest rate of positive tests was 10075, which covers a narrow strip from East 76th to 80th streets and includes Lenox Hill Hospital. About 14.1 percent of antibody tests came back positive for residents in that area.

The lowest rate of positive tests was in 10065, the neighborhood's southernmost ZIP code, where about 12.6 percent of residents' tests came back positive.

Citywide, Manhattan had the lowest rate of positive tests out of all five boroughs, with about 19 percent of tests coming back positive. The Bronx had the highest rate, at about 33 percent.

Percent positive antibody tests by Upper East Side ZIP code:

• 10065: 12.6 percent (8,492 tested, 1,070 positive)
• 10021: 13.1 percent (13,189 tested, 1,732 positive)
• 10075: 14.1 percent (7,203 tested, 1,019 positive)
• 10028: 13.6 percent (12,728 tested, 1,733 positive)
• 10128: 12.7 percent (16,216 tested, 2,065 positive)
• Total: 13.2 percent (57,828 tested, 7,619 positive)

The antibody tests, or serology tests, indicate whether a person may have been exposed to the coronavirus by measuring their bloodstream for signs that their immune system produced proteins, called antibodies, to fight off the virus.

Mayor Bill de Blasio announced Tuesday that the city's website for coronavirus data would start including the results of antibody tests, but experts warn that such data should be taken with a grain of salt.

First, antibody test results aren't always accurate.

Positive tests results could mean the person has antibodies from an infection with a virus in the same family as the coronavirus, according to the U.S. Centers for Disease Control and Prevention. The chance of receiving a false negative can be as high as 30 percent, depending on when the test is conducted, according to a Harvard Medical School blog post.

The data also may not accurately reflect the prevalence of antibodies among all neighborhood residents or New York City residents, because people who have been ill with COVID-19 symptoms or were exposed to the virus may be likelier to seek out antibody testing, the city wrote in a disclaimer about the dataset.

"We will be the first jurisdiction in the nation to present our antibody data this way," de Blasio told reporters. "While there is still much to learn about the science of COVID-19 antibody testing, it is an important element to consider when understanding the epidemiology of COVID."

Patch reporter Maya Kaufman contributed to this report.