Neuraminidase inhibitors for influenza B virus infection: Efficacy and resistance

Many aspects of the biology and epidemiology of influenza B viruses are far less studied than for influenza A viruses, and one of these aspects is efficacy and resistance to the clinically available antiviral drugs, the neuraminidase (NA) inhibitors (NAIs). Acute respiratory infections are one of the leading causes of death in children and adults, and influenza is among the few respiratory infections that can be prevented and treated by vaccination and antiviral treatment. Recent data has suggested that influenza B virus infections are of specific concern to pediatric patients because of the increased risk of severe disease. Treatment of influenza B is a challenging task for the following reasons: 1. NAIs (e.g., oseltamivir and zanamivir) are the only FDA-approved class of antivirals available for prophylaxis and treatment of influenza. 2. The data suggest that oseltamivir is less effective than zanamivir in pediatric patients. 3. Zanamivir is not prescribed to patients younger than 7 years of age. 4. Influenza B viruses are less susceptible than influenza A viruses to NAIs in vitro. 5. Although the level of resistance to NAIs is low, the number of different molecular markers of resistance is higher than for influenza A viruses, and they are not well defined. 6. The relationship between levels of NAI phenotypic resistance and known molecular markers, frequency of emergence, transmissibility, and fitness of NAI-resistant variants are not well established. This review presents current knowledge of the efficacy of NAIs for influenza B virus and antiviral resistance in clinical, surveillance, and experimental studies. (C) 2013 Elsevier B.V. All rights reserved.