While the first case of COVID-19 was confirmed in New York City March 1, the virus was present as early as mid-February, and more than 1.7 million have been infected, according to a study published Nov. 3 in Nature.
Researchers analyzed 10,691 blood plasma samples in weekly intervals between February and July from patients at New York City-based Mount Sinai Health System. After measuring antibodies from two groups, a positive control group from patients seeking urgent care at the health system's emergency departments and a second group seeking routine care visits, they determined that at least 1.7 million New Yorkers have been infected with SARS-CoV-2 so far, with a 0.97 percent fatality rate — 10 times higher than the flu.
The positive control group, or "urgent care" group, included 4,101 samples and was meant to detect increasing infections in patients with moderate to severe COVID-19. The routine care group included 6,590 samples and was intended to represent the general population, since scheduled visits were not related to COVID-19.
Researchers said antibody presence increased in both groups at different rates, with the urgent care group seeing a sharp rise. Positive samples were detected as early as mid-February and leveled out around 20 percent across both groups after cases started to let up at the end of May. Antibody levels stabilized between May and July.
"We show that the infection rate was relatively high during the first wave in New York but is far from seroprevalence that might indicate herd immunity," Florian Krammer, PhD, study author and vaccinology professor at Mount Sinai's Icahn School of Medicine, said in a news release. "Knowing the detailed dynamics of the seroprevalence shown in this study is important for modeling seroprevalence elsewhere in the country."
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