The natural history of influenza infection in the severely immunocompromised vs nonimmunocompromised hosts

Abstract

Introduction: Medical advances have led to an increase in the world's population of immunosuppressed individuals. The most severely immunocompromised patients are those who have been diagnosed with a hematologic malignancy, solid organ tumor, or who have other conditions that require immunosuppressive therapies and/or solid organ or stem cell transplants.

Materials and methods: Medically attended patients with a positive clinical diagnosis of influenza were recruited prospectively and clinically evaluated. Nasal washes and serum were collected. Evaluation of viral shedding, nasal and serum cytokines, clinical illness, and clinical outcomes were performed to compare severely immunocompromised individuals to nonimmunocompromised individuals with influenza infection.

Results: Immunocompromised patients with influenza had more severe disease/complications, longer viral shedding, and more antiviral resistance while demonstrating less clinical symptoms and signs on clinical assessment.

Conclusions: Immunocompromised patients are at risk for more severe or complicated influenza induced disease, which may be difficult to prevent with existing vaccines and antiviral treatments. Specific issues to consider when managing a severely immunocompromised host include the development of asymptomatic shedding, multi-drug resistance during prolonged antiviral therapy, and the potential high risk of pulmonary involvement.

Clinical trials registration: ClinicalTrials.gov identifier NCT00533182.

Keywords: immunocompromised host; influenza; influenza A; stem cell transplant.

Figure 1.

Length of viral shedding. Patients were sampled daily until they had a negative clinical diagnostic test. Significantly longer shedding was detected in the immunocompromised group. Each dot represents an individual patient's length of shedding. Solid lines represent the mean (immunocompromised 19.04 days vs nonimmunocompromised 6.38 days; P value .0466). Dotted lines represent the median (immunocompromised 8.0 days vs nonimmuncompromised 5.0 days; P value .0130).

Figure 2.

Cytokines levels detected in nasal wash. Seventeen cytokines were measured in nasal washes, and the 7 represented here were elevated when compared to a mean of 3 healthy controls. Error bars represent the standard error of the mean.

Figure 3.

Cytokines detected in serum. Seventeen cytokines were measured in serum, and the 7 represented here were elevated when compared to a mean of 3 healthy controls. Error bars represent the standard error of the mean.