Influenza in immunosuppressed populations: a review of infection frequency, morbidity, mortality, and vaccine responses

Abstract

Patients that are immunosuppressed might be at risk of serious influenza-associated complications. As a result, multiple guidelines recommend influenza vaccination for patients infected with HIV, who have received solid-organ transplants, who have received haemopoietic stem-cell transplants, and patients on haemodialysis. However, immunosuppression might also limit vaccine responses. To better inform policy, we reviewed the published work relevant to incidence, outcomes, and prevention of influenza infection in these patients, and in patients being treated chemotherapy and with systemic corticosteroids. Available data suggest that most immunosuppressed populations are indeed at higher risk of influenza-associated complications, have a general trend toward impaired humoral vaccine responses (although these data are mixed), and can be safely vaccinated--although longitudinal data are largely lacking. Randomised clinical trial data were limited to one study of HIV-infected patients with high vaccine efficacy. Better trial data would inform vaccination recommendations on the basis of efficacy and cost in these at-risk populations.

Figure. Percentage of immunosuppressed patients and healthy controls with protective postvaccination influenza titres

Data are only presented for proportions of patients with H3N2 serotype of influenza A, which is typically associated with higher risk of admission to hospital and death than the H1N1 serotype or influenza B., Protective haemagglutination inhibition (HI) titre for studies was 1:40 or greater unless otherwise noted. Studies without healthy control groups are not presented. No studies provided data on haemopoietic stem-cell transplant recipients relevant to these figures. Also excluded are data for corticosteroid users, because of inability to extract relevant data for figures. Results in patients with HIV infection (A), stratified by CD4+ T cell counts, and healthy controls. Fowke and colleagues not shown, because CD4 strata were not readily integrated with more conventional CD4 strata above. Brydak and colleagues did not include healthy control group, but data were provided for CD4 strata, and therefore included. Results in solid-organ transplant recipients and healthy controls (B): Hayney and colleagues data extracted from published figures. Dengler and colleagues reported percentage with either HI titer 1:40 or greater or with four-fold or greater rise in HI titre postvaccination. Birdwell and colleagues reported HI titer of 1:32 or greater. Results in patients treated with chemotherapy for malignancies and healthy controls (C): Feery and colleagues and Gribabis and colleagues data extracted from published figures. Stiver and colleagues reported HI titre of 1:32 or greater. Results in patients on hemodialysis and healthy controls (D): Beyer and colleagues reported HI titre of 1:100 or greater. Rautenburg and colleagues data extracted from published figures and reported IgG titre of 1:2 or greater. Antonen and colleagues data extracted from published figures.