COVID-19 and flu infections raise the risk of a broad range of health problems, and the impact of these infections can stretch beyond the initial illness. New findings from researchers at Washington University in St. Louis suggest that seasonal viruses should be viewed as potential contributors to chronic disease rather than just acute illnesses. The work appeared in Lancet Infectious Diseases.
Researchers analyzed medical records from about 81,000 patients hospitalized with COVID-19 and roughly 11,000 patients hospitalized with seasonal influenza. The study encompassed the timeframes during which the delta and omicron variants were circulating.
Compared with those who recovered from flu, patients who survived COVID-19 had a 50% higher risk of death. The study explored associations between viral infections and the elevated risk of 94 diseases across all organ systems. COVID-19 infection raised the risk for 64 diseases, while influenza increased the risk for six. When the virus affected multiple organ systems, the flu primarily hit the lungs, but COVID-19 showed broader organ involvement.
In both illnesses, more than half of the deaths and the emergence of new diseases occurred within a few months after infection, rather than during the acute 30-day period.
As one of the study’s authors, clinical epidemiologist Ziyad Al-Ali, notes, the pandemic changed how viral infections are perceived. Before the pandemic, many infections were viewed as short-term ailments that resolved quickly. The data now indicate that some individuals endure serious long-term health issues, and this reality should be recognized. Viral infections should be understood as important drivers of chronic disease rather than merely temporary illnesses (Lancet Infectious Diseases study, attribution).
Vaccination against both COVID-19 and seasonal flu remains a key strategy to prevent severe illness, reduce hospitalizations, and lower the risk of death. The study highlights that vaccination is particularly crucial for vulnerable groups, including older adults and individuals with compromised immune systems.
Earlier research remains relevant in showing a path toward mitigating the spread and impact of harmful microbes within the gut and other body systems, underscoring the broader health implications of respiratory viruses beyond their immediate symptoms (Lancet Infectious Diseases study, attribution).