Even though scientists are still learning about long COVID, they’re now acknowledging that COVID-19 isn’t the only ailment that can linger. Enter the term “long flu.”
A team from Washington University School of Medicine in St. Louis and the Veterans Affairs St. Louis Health Care System found that people who were hospitalized with seasonal flu can suffer long-term, negative health effects (especially in the lungs and airways). The findings were published Thursday in The Lancet Infectious Diseases.
Researchers compared the flu virus and SARS-CoV-2. Upon analysis, they found that people hospitalized for either virus had a higher risk of being readmitted, dying or having multiple health problems in organ systems. The time of the highest risk was within 30 days of the initial infection.
The team followed up on people up to 18 months after the initial infection. In addition to investigating readmissions and death risks, researchers evaluated 94 adverse health outcomes that can affect a person’s organs.
Data came from the US Department of Veterans Affairs, and it included details on 81,280 people hospitalized for COVID-19 between March 1, 2020, and June 30, 2022. The data also included 10,985 people who were hospitalized for seasonal flu from Oct. 1, 2015, through Feb. 28, 2019.
Over the course of the 18-month study period, people with COVID-19 had a 50% higher risk of death than the flu, the team noted. Notably, the overall risk and occurrence of death, hospital admissions and impacts to organ systems were substantially higher among COVID-19 patients than among those who had seasonal influenza, the team found. The flu has higher risks on the pulmonary system than COVID-19, though, they added.
Vaccination didn’t play a protective role, the authors noted.
“Five years ago, it wouldn’t have occurred to me to examine the possibility of a ‘long flu,’” Ziyad Al-Aly, MD, a clinical epidemiologist at Washington University, said in a statement. “A major lesson we learned from SARS-CoV-2 is that an infection that initially was thought to only cause brief illness also can lead to chronic disease. This revelation motivated us to look at long-term outcomes of COVID-19 versus flu.”
Both COVID-19 and the flu led to long-term health problems, and the long-term health loss was worse than the problems that these patients endured in the early phase of the infection, he added. “Long COVID is much more of a health problem than COVID, and long flu is much more of a health problem than the flu,” Al-Aly added.
This corresponded to about eight more deaths per 100 persons in the COVID-19 group than among those with the flu. People with COVID-19 had a higher risk of readmission and admission to the intensive care unit. For every 100 people in each group, there were 20 more hospital admissions and nine more ICU admissions in those with COVID-19 compared to those with the flu.
Although people who had COVID-19 displayed a greater risk of health loss compared to those with the flu, infection with either virus had significant risk of disability and disease. The researchers found those with COVID-19 showed an increased risk of 68% of health conditions examined across all organ systems (64 of the 94 adverse health outcomes studied). In terms of the flu, it was linked to having an elevated risk of 6% of health conditions (six of the 94), mostly in the respiratory system.
