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Fluorescence-based Neuraminidase Inhibition Assay to Assess the Susceptibility of Influenza Viruses to The Neuraminidase Inhibitor Class of Antivirals
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Characteristics of patients with oseltamivir-resistant pandemic (H1N1) 2009, United States

Samuel B Graitcer1, Larisa Gubareva, Laurie Kamimoto

  • 1Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA.

Emerging Infectious Diseases
|February 5, 2011
PubMed

Insights

Oseltamivir-resistant pandemic (H1N1) 2009 virus was found in 0.5% of cases. Most resistant infections occurred in immunocompromised patients previously treated with oseltamivir, with no evidence of community spread.

Area of Science:

  • Virology
  • Infectious Diseases
  • Public Health

Background:

  • Influenza A (H1N1)pdm09 virus emerged in 2009.
  • Oseltamivir is a key antiviral medication for influenza treatment.
  • Antiviral resistance is a growing public health concern.

Purpose of the Study:

  • To determine the prevalence of oseltamivir resistance in pandemic (H1N1) 2009 viruses.
  • To identify risk factors associated with oseltamivir-resistant infections.

Main Methods:

  • Analysis of pandemic (H1N1) 2009 viruses submitted to a US surveillance system between April 2009 and June 2010.
  • Phenotypic or genotypic testing for oseltamivir resistance.
  • Review of patient clinical data, including immunocompromised status and oseltamivir treatment history.

Main Results:

  • Thirty-seven (0.5%) of 6,740 pandemic (H1N1) 2009 viruses exhibited oseltamivir resistance.
  • The majority of patients (76%) with resistant infections were severely immunocompromised.
  • Most patients with resistant infections (89%) had received oseltamivir prior to specimen collection.

Conclusions:

  • Oseltamivir resistance in pandemic (H1N1) 2009 viruses was low during the study period.
  • Severely immunocompromised individuals with prior oseltamivir exposure are at higher risk for resistant infections.
  • No evidence of widespread community circulation of oseltamivir-resistant pandemic (H1N1) 2009 viruses was observed.

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