Approximately 75% of the deaths reported to the New York City Department of Health and Mental Hygiene (NYC DOHMH) between March 11, 2020, and May 2, 2020, were found to be in excess of the seasonal expected baseline, according to a report from the NYC DOHMH COVID-19 Response Team published in the Morbidity and Mortality Weekly Report.
As counting only confirmed or probable coronavirus disease 2019 (COVID-19)-associated deaths is presumed to underestimates the number of deaths attributable to the pandemic, the researchers aimed to provide an estimation of all-cause excess deaths, referring to the number of deaths above expected seasonal baseline levels, as this calculation might provide a more accurate measure of the effect of the pandemic. To determine the excess deaths in NYC for the period March 11-May 2, 2020, mortality data from the period January 1, 2015, through May 2, 2020, were obtained. The difference between the seasonally expected baseline number and the reported number of all-cause deaths was then calculated.
A total of 32,107 deaths were reported to the DOHMH, 24,172 (95% CI, 22,980-25,364) of which were found to be in excess of the seasonal expected baseline. Approximately 57% (13,831) of the deaths were associated with laboratory-confirmed COVID-19, 21% (5048) were recorded as probable COVID-19-associated deaths, and 22% (5293) were excess deaths not confirmed as being associated with COVID-19, although they may have been directly or indirectly attributable to the pandemic.
The researchers noted that it is not possible to know how many of these excess deaths occurred in persons infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or were as an indirect result of the pandemic. They state that although their approach cannot account for causal factors, it does account for temporal factors associated with SARS-CoV-2 that might affect death rates.
All-cause mortality surveillance “provides a faster and more inclusive measure of the pandemic’s impact on mortality than does relying only on national COVID-19 reporting mechanisms,” concluded the researchers.
New York City Department of Health and Mental Hygiene (DOHMH) COVID-19 Response Team. Preliminary estimate of excess mortality during the COVID-19 outbreak – New York City, March 11-May 2, 2020. MMWR Mortal Wkly Rep. 2020;69(19):603-605.