New York State conducted an antibody testing study [
source], showing that 12.3% of the population in the state had COVID-19 antibodies as of May 1, 2020. The survey developed a baseline infection rate by testing 15,103 people at grocery stores and community centers across the state over the preceding two weeks. The study provides a breakdown by county, race (White 7%, Asian 11.1%, multi/none/other 14.4%, Black 17.4%, Latino/Hispanic 25.4%), and age, among other variables.
19.9% of the population of New York City had COVID-19 antibodies. With a population of 8,398,748 people in NYC [
source], this percentage would indicate that
1,671,351 people had been infected with SARS-CoV-2 and had recovered as of May 1 in New York City. The number of confirmed cases reported as of May 1 by New York City was
166,883 [
source], more than 10 times less.
As of May 1, New York City reported 13,156 confirmed deaths and 5,126 probable deaths (deaths with COVID-19 on the death certificate but no laboratory test performed), for a total of 18,282 deaths [
source]. The CDC on May 11 released its "
Preliminary Estimate of Excess Mortality During the COVID-19 Outbreak — New York City, March 11–May 2, 2020" [
source] in which it calculated an estimate of actual COVID-19 deaths in NYC by analyzing the "excess deaths" (defined as "the number of deaths above expected seasonal baseline levels, regardless of the reported cause of death") and found that, in addition to the confirmed and probable deaths reported by the city, there were an estimated 5,293 more deaths to be attributed. After adjusting for the previous day (May 1), we get 5,148 additional deaths, for a total of actual deaths of 13,156 confirmed + 5,126 probable + 5,148 additional excess deaths calculated by CDC =
23,430 actual COVID-19 deaths as of May 1, 2020 in New York City.
Actual Cases with an outcome as of May 1 = estimated actual recovered (1,671,351) + estimated actual deaths (23,430) =
1,694,781.
Infection Fatality Rate (IFR) = Deaths / Cases = 23,430 / 1,694,781 =
1.4% (1.4% of people infected with SARS-CoV-2 have a fatal outcome, while 98.6% recover).