In the first 3 months of the US coronavirus epidemic, the number of excess deaths in the United States was 122,300, 28% more than the reported number of deaths from COVID-19, according to a published observational study today in JAMA Internal Medicine.
Led by researchers at Yale University, the study analyzed data from the National Center for Health Statistics and the Centers for Disease Control and Prevention to better characterize the burden of the new coronavirus during the outbreak of the epidemic in the United States and Compare death counts with the same period in previous years.
Substantial variation between states
From March 1 to May 30, there were approximately 781,000 deaths from all causes in 48 states, 95,235 officially attributed to COVID-19, leaving 122,300 more than would be expected during that period. The researchers said that while they cannot classify deaths due to COVID-19, flu activity had dropped to historically low levels in March.
In several states, deaths occurred before the availability of COVID-19 diagnostic tests, and therefore were not counted as coronavirus deaths. The estimated number of excess deaths varied significantly between states.
For example, in New York City, deaths from all causes were seven times higher than the baseline at the peak of the pandemic, with 25,100 excess deaths, of which 26% were not attributed to COVID -19. Elsewhere in New York, excess deaths were only twice the initial value, with 12,300 excess deaths.
Other states with a high number of excess deaths were New Jersey, Massachusetts, Louisiana, Illinois, and Michigan, while there were few or no excess deaths in some smaller central states and northern New England.
The gap between deaths attributed to COVID-19 and the estimated number of excess deaths from all causes also varied across states, with California reporting 4,046 coronavirus deaths and 6,800 excess deaths, leaving 41% of excess deaths not attributed to COVID-19.
The gaps were even wider in Texas, with 55% of excess deaths not classified as due to the coronavirus, and in Arizona, where 53% of excess deaths were attributed to causes other than COVID-19. Minnesota showed the best agreement, with only 12% of excess deaths not attributed to COVID-19.
Moment of further testing
The authors noted that the discrepancies may be due in part to the intensity and timing of the increased evidence. For example, in states like Texas and California, excess all-cause death rates occurred several weeks before COVID-19 diagnostic tests were widely available. Conversely, states like Massachusetts and Minnesota, where the gaps were smaller, were able to increase testing before or at the same time that excess deaths increased.
The differences could also be the result of guidelines on recording suspicious but unconfirmed deaths as due to COVID-19 and the location of death. For example, nursing home deaths are more likely to be correctly attributed to the coronavirus because they are more likely to be recognized as part of the epidemic.
The reported increase in excess deaths could also reflect a higher number of deaths directly caused by the virus, avoid visiting the health care setting and the decrease in deaths due to car accidents or air pollution.
According to the researchers, official death counts were better combined with estimates of excess deaths as the pandemic progressed, perhaps due to increased testing and recognition of clinical signs and symptoms of COVID-19. For example, New York City added another 5,048 COVID-19 deaths after carefully reviewing death certificates, generating a number that more closely aligns with researchers’ estimates.
The authors noted that in the first part of the pandemic, when diagnostic tests were especially scarce, only 10-15% of all coronavirus infections were diagnosed. “These findings demonstrate that estimates of the number of COVID-19 deaths based on excess mortality from all causes may be more reliable than those that rely solely on reported deaths, particularly in places that lack widespread evidence,” they wrote.
