Increased 30-day mortality risk in COVID-19 compared with seasonal influenza

This study aimed to compare 30-day all-cause mortality between patients with COVID-19 and those with seasonal influenza in South Korea.

This nationwide, population-based cohort study used the National Health Insurance Claims Database, including individuals newly diagnosed with COVID-19 or influenza between July 2022 and December 2023. The primary outcome was 30-day all-cause mortality. Logistic regression analysis was conducted to compare mortality risks, adjusting for demographic and clinical covariates.

A total of 12,802,169 patients with COVID-19 and 2,888,777 patients with influenza were analyzed. COVID-19 was associated with significantly higher 30-day all-cause mortality compared with influenza (adjusted odds ratio [aOR]: 1.76; 95% confidence interval: 1.60-1.94). This elevated risk remained consistent across most subgroups defined by age, sex, health care utilization, and comorbidities. Particularly higher risks were observed among adults aged 18-64 years (aOR: 2.93), hospitalized patients (aOR: 2.55), and those with myocardial infarction (aOR: 2.24).

COVID-19 is associated with markedly higher short-term mortality than influenza across diverse clinical and demographic subgroups. These findings underscore the ongoing need for vigilant prevention efforts and vaccination. This study represents the first large-scale nationwide analysis in Asia conducted in the post-COVID-19 era.