November 08, 2013
2 min read

Flu more severe in immunocompromised patients

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Patients who are immunocompromised are at increased risk for more severe influenza disease that appears to be more difficult to prevent and treat, according to research published in Clinical Infectious Diseases.

“The purpose of this study was to understand influenza-induced disease in these individuals to develop further basic knowledge that can lead to novel strategies for disease prevention and treatment,” Matthew J. Memoli, MD, MS, director of the LID Clinical Studies Unit, Viral Pathogenesis and Evolution Section, Laboratory of Infectious Diseases at the National Institute of Allergy and Infectious Diseases, told Infectious Disease News. “We demonstrated that influenza-induced disease is different in immunocompromised hosts and that a unique set of issues must be considered by physicians when providing care to these patients.”

Matthew Memoli, MD 

Matthew J. Memoli

The study included 86 patients who had an influenza diagnosis during a 3-year period between 2008 and 2011. Thirty-two patients were classified as severely immunocompromised, mainly due to treatment with hematopoietic stem cell transplant or immunosuppressive therapy. The most common condition was hematologic malignancy. The remaining 54 patients were not immunocompromised.

More patients in the non-immunocompromised group had higher prevalence of symptoms and abnormalities, including pulmonary abnormalities. All of the immunocompromised patients required hospitalization when diagnosed with influenza vs. 16 patients (29.6%) who were not immunocompromised. The immunocompromised patients also had a longer length of illness, with a mean shedding of 19 days, compared with 6.4 days for non-immunocompromised patients.

Approximately 47% of the patients in the study had received an influenza vaccination within the past year, but still became ill. More patients in the non-immunocompromised group were vaccinated (59%) compared with the immunocompromised group (25%).

Memoli said that physicians treating immunocompromised individuals should take into account that they may not present with the same symptoms or severity of symptoms of influenza as healthy people. Physicians should also consider that even though they have fewer, less severe symptoms, these patients are at higher risk for developing lower respiratory tract disease, more severe disease and more complications, he said.

“With the advent of modern medical treatments, we have created a population of individuals living longer with many diseases, but these treatments and/or diseases leave individuals vulnerable to the complications of viruses like influenza,” Memoli said.

Memoli said that future research should focus on investigating how the virus evolves in a single host who is infected for an extended period, how fast drug resistance can develop, and whether resistance can be transmitted to others.

Matthew Memoli, MD, MS, can be reached at

Disclosure: The researchers report no relevant financial disclosures.