To determine if COVID-19 was overreported as an underlying cause of death, researchers calculated the overreporting adjustment factor and
compared the ratio of reporting COVID-19 as a multiple—or contributing—cause of death versus an underlying cause of death on death certificates from 2020 to 2022. They also examined how “pneumonia and influenza” were reported on death certificates from 2010 to 2022.
An overreporting adjustment factor for mortality is a statistical correction applied to
mortality data to account for the propensity of certain death counts reported more frequently or inaccurately than others. It typically involves comparing reported death counts to a more accurate independent benchmark, which helps ensure data reflect the true incidence of deaths in a population. Here, the researchers chose pneumonia and influenza because the conditions are similar in nature to COVID-19, and they could compare patterns using mortality data before and after the pandemic began in 2020.
According to the preprint,
data show COVID-19 was systematically overreported as an underlying cause of death during the pandemic by an average of about three times for all ages compared to influenza and pneumonia during the same period—and was highest in those aged 15 to 54. Additionally, only about one-third of influenza and pneumonia-related deaths were reported as underlying causes, whereas almost all COVID-19-related deaths were reported as “deaths from COVID-19.”