An estimated 1.7 million New Yorkers have had COVID-19 — six times the official count, a study released Tuesday suggests.
Researchers from the Icahn School of Medicine at Mount Sinai also found the coronavirus was circulating through the five boroughs “long before” the first recorded case, the study published in Nature states.
“We now know there were many asymptomatic and mild to moderate cases that likely went undetected,” Dr. Emilia Mia Sordillo, an attending physician in infectious diseases at the medical school and a senior author on the paper, said in a news release. “In this study, we aimed to understand the dynamics of infection in the general population and in people seeking urgent care.”
The researchers used more than 10,000 plasma samples taken from the beginning of February to July during routine health visits and COVID-19 hospitalizations to reach their conclusion.
Two groups of patients were used for the study. The first group of 4,101 plasma samples were taken during hospital visits and admissions, and served as a positive control group to track COVID-19 infections as the pandemic progressed in the Big Apple.
The second dataset of 6,509 plasma samples were obtained during OB/GYN visits, labor and deliveries, oncology-related visits, elective and transplant surgery hospitalizations and other regular and routine doctor visits, Mount Sinai said.
“Researchers reasoned that these samples might resemble the general population more closely because the purposes for these scheduled visits were unrelated to acute SARS-CoV-2 infection,” the hospital said. “The routine care group had a more balanced age distribution that more closely resembled the general population adult population.”
Researchers found plasma containing COVID-19 antibodies were detected “as early as mid-February” — several weeks before the first official cases were reported in the city — and “leveled out at slightly above 20% in both groups after the epidemic wave subsided by the end of May,” the study shows.
Using those numbers, scientists extrapolated that 20% of New Yorkers likely had the virus already.
Further, the scientists found antibody levels “stayed stable” from May to July, which suggests immunity could last for at least a few months but does not rise to the level of herd immunity.