The conversation, CC BY-ND
The death toll in the United States through July 2020 is 8% to 12% higher than it would have been if the coronavirus pandemic had never happened. That is at least 164,937 deaths above the number expected for the first seven months of the year – 16,183 more than the number so far attributed to COVID-19 for this period – and it could be as high as 204,691.
Death of dead
When someone dies, the death certificate records a direct cause of death, along with a maximum of three underlying circumstances that “initiate the events that result in death.” The certificate is submitted to the local health department, and the details are reported to the National Center for Health Statistics.
As part of the National Vital Statistics System, the NCHS then uses this information in various ways, such as tabulating the leading causes of death in the United States – currently heart disease, followed by cancer. Sometime this fall, COVID-19 is likely to be the third leading cause of death by 2020.
Projects from the past
Calculating excessive deaths requires a comparison with what would have happened if COVID-19 had not existed. Of course, it is not possible to observe what did not happen, but it is possible to estimate it with historical data. The Centers for Disease Control and Prevention does this using a statistical model, based on the previous three years of mortality data, and includes seasonal trends and adjustments for data reporting delays.
That, looking at what has happened in the past three years, the CDC is projecting what may have been. Using a statistical model, they are also able to calculate the uncertainty in their estimates. This allows statisticians like me to assess whether the observed data look unusual compared to projections.
The number of excessive deaths is the difference between the projections of the model and the actual observations. The Centers for Disease Control and Prevention also calculates an upper threshold for the estimated number of deaths – which helps determine when the number of deaths observed is unusually high compared to historical trends.
Clearly seen in a graph of these data is the spike in death that begins mid-March 2020 and continues to the present. You can also see another period of excessive deaths from December 2017 to January 2018, attributed to an unusual virulent flu strain that year. The magnitude of the excessive deaths in 2020 makes it clear that COVID-19 is much less than flu, even compared to a bad flu year like 2017-18, when an estimated 61,000 people in the US died from the disease.
The large spike in deaths in April 2020 coincided with the outbreak of coronavirus in New York and the Northeast Polder, after which the number of excessive deaths dropped regularly and substantially until July, when it began to increase again. This current uptick in excessive deaths is due to the outbreaks in the South and West that have been occurring since June.
The data tells the story
It does not take a sober statistical model to show that the coronavirus pandemic causes substantially more deaths than would otherwise have happened.
The number of deaths officially attributed by the CDC to COVID-19 in the United States was 148,754 by Aug. 1. Some people who are skeptical about aspects of the coronavirus suggest that these are deaths that would have happened anyway, perhaps because COVID-19 is particularly deadly to the elderly. Others believe that because the pandemic has changed lives so drastically, the increase in COVID-19-related deaths is likely to be offset by decreases in other causes. But none of these possibilities are true.
In fact, the number of excessive deaths at present is the number more than attributed to COVID-19 by more than 16,000 people in the US. What is behind that difference is not yet clear. COVID-19 deaths could be undercounted, as the pandemic could also escalate into other types of deaths. It’s probably something of both.
Despite that reason, the COVID-19 pandemic has resulted in substantially more deaths than would otherwise have happened … and it is not over yet.
Ronald D. Fricker Jr., Professor of Statistics and Associate Dean for Faculty Affairs and Administration, Virginia Tech
This article was republished from The Conversation under a Creative Commons license. Read the original article.
