Influenza vaccination in HIV-infected patients

Introduction
One of the most serious threats for people infected with human immunodeficiency virus (HIV) is the risk of influenza co-infection and complications thereof. Not only is this population fundamentally more susceptible to flu but also prolonged replication and excretion of the virus, longer illness period, higher complication rate, flu-associated mortality, and risk of cardiovascular disease have all been noted.

Material and methods
The aim of our study was to assess vaccine efficacy against influenza in HIV-infected patients in various stages of the disease in comparison to a control group and estimate the influence of the vaccine on respiratory system infection rates. We prospectively studied 78 patients. Our study group included 47 patients with HIV and 31 healthy volunteers. The participants were immunised with TIV (trivalent influenza vaccine). Humoral response as an anti-AH1N1 (A/Brisbane/59/07), -AH3N2 (A/Brisbane/10/07), and -B strain (B/Florida/4/06) haemagglutinin antibody titre was measured. The assay was performed twice: before administration of the vaccine and a month after.

Results
The HIV-infected group exhibited a weaker immune response than the control group; however, the immunisation did provide partial protection against influenza. Vaccine efficacy was similar, regardless of CD4 count. Trivalent influenza vaccine successfully prevented influenza-associated bacterial pneumonia.

Conclusions
The study demonstrates that routine vaccination against influenza in HIV-infected patients, regardless of immune system deficiency, is substantiated.