'Long flu' has emerged as a consequence similar to long COVID

Since the COVID-19 pandemic began, extensive research has emerged detailing the virus's ability to attack multiple organ systems, potentially resulting in a set of enduring and often disabling health problems known as long COVID. Now, new research from Washington University School of Medicine in St. Louis and the Veterans Affairs St. Louis Health Care System indicates that people hospitalized with seasonal influenza also can suffer long-term, negative health effects, especially involving their lungs and airways.

The new study comparing the viruses that cause COVID-19 and the flu also revealed that in the 18 months after infection, patients hospitalized for either COVID-19 or seasonal influenza faced an increased risk of death, hospital readmission, and health problems in many organ systems. Further, the time of highest risk was 30 days or later after initial infection. The findings are published Dec. 14 in The Lancet Infectious Diseases.

Regarding both viruses, patient vaccination status did not affect results. Those in the COVID-19 cohort were hospitalized during the pre-delta, delta and omicron eras.

During the overall 18-month study period, patients who had COVID-19 faced a 50% higher risk of death than those with seasonal influenza. This corresponded to about eight more deaths per 100 persons in the COVID-19 group than among those with the flu.

Although COVID-19 showed a greater risk of health loss than seasonal influenza, infection with either virus carried significant risk of disability and disease. The researchers found COVID-19 exhibited increased risk of 68% of health conditions examined across all organ systems (64 of the 94 adverse health outcomes studied), while the flu was associated with elevated risk of 6% of health conditions (six of the 94) – mostly in the respiratory system.

Also, over 18 months, COVID-19 patients experienced an increased risk of hospital readmission as well as admission to an intensive care unit (ICU). For every 100 persons in each group, there were 20 more hospital admissions and nine more ICU admissions in COVID-19 than flu.

Reference: ‘Long flu’ has emerged as a consequence similar to long COVID; The Lancet Infectious Diseases, DOI: 10.1016/S1473-3099(23)00684-9