The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) first emerged in December 2019 in Wuhan, China, and rapidly grew into a global pandemic.1 Without adequate capacity to test for SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19), during the early part of the pandemic, laboratory-confirmed cases captured only an estimated 10% to 15% of all infections.2 As a result, estimating the number of deaths caused by COVID-19 is a challenge.
Questions have been raised about the reported tallies of deaths related to COVID-19 in the United States. Some officials have raised concerns that deaths not caused by the virus were improperly attributed to COVID-19, inflating the reported tolls. However, given the limited availability of viral testing and the imperfect sensitivity of the tests,3,4 there have likely been a number of deaths caused by the virus that were not counted. Furthermore, if patients with chronic conditions turn away from the health care system because of concerns about potential COVID-19 infection, there could be increases in certain categories of deaths unrelated to COVID-19. In the midst of a large outbreak, there is also an unavoidable delay in the compilation of death certificates and ascertainment of causes of death. Overall, the degree of testing, criteria for attributing deaths to COVID-19, and the length of reporting delays are expected to vary between states, further complicating efforts to obtain an accurate count of deaths related to the pandemic.
To estimate the mortality burden of a new infectious agent when there is a lack of comprehensive testing, it is common to assess increases in rates of death beyond what would be expected if the pathogen had not circulated.5–7 The “excess death” approach can be applied to specific causes of death directly related to the pathogen (eg, pneumonia or other respiratory conditions), or this approach can be applied to other categories of deaths that may be directly or indirectly influenced by viral circulation or pandemic interventions (eg, cardiac conditions, traffic injuries, or all causes). The excess deaths methodology has been used to quantify official undercounting of deaths for many pathogens, including pandemic influenza viruses and HIV.7–9
In this study, we estimate the excess deaths due to any cause in each week of the COVID-19 pandemic across the United States. We compare these estimates of excess deaths with the reported numbers of deaths due to COVID-19 in different states and evaluate the timing of these increases in relation to testing and pandemic intensity. These analyses provide insights into the burden of COVID-19 in the early months of the outbreak in the United States and serve as a surveillance platform that can be updated as new data accrue.