Clinical Effectiveness of Oseltamivir and Zanamivir for Treatment of Influenza A Virus Subtype H1N1 with the H274Y Mutation: A Japanese, Multicenter Study of the 2007–2008 and 2008–2009 Influenza Seasons

Abstract

The effectiveness of oseltamivir, but not that of zanamivir, decreased significantly for H1N1 virus infection during the 2008-2009 season.

Clinical and virologic outcomes in patients with oseltamivir‐resistant seasonal influenza A (H1N1) infections: results from a clinical trial

“…Trends suggestive of a shorter duration of clinical symptoms and viral shedding among the groups treated early with oseltamivir were found, but because of our small sample size, these findings may be explained by chance. In addition, these results are not consistent with a limited number of studies that have assessed the effectiveness of oseltamivir treatment in patients with oseltamivir‐resistant influenza A (H1N1) infection 5 , 6 , 7 . Our sample size was small because of the unplanned early study termination in the setting of antiviral resistance.…”

Phase III Randomized, Double-Blind Study Comparing Single-Dose Intravenous Peramivir with Oral Oseltamivir in Patients with Seasonal Influenza Virus Infection

“…Given the possibility that oseltamivir may have been ineffective in the study population (approximately 50% of patients were infected with the less sensitive H274Y mutant of A/H1N1), the lack of a placebo group may have undermined the significance of the study. Kawai et al found that the clinical efficacy of oseltamivir against the H1N1 virus with H274Y was reduced, especially among children (10,11). In clinical trials with laninamivir (CS-8958) in the same season, this drug provided a shorter duration of influenza than did oseltamivir in the H1N1 subpopulation in a pediatric trial, but not in an adult trial (20,23).…”

Incomplete Inhalation of Laninamivir Octanoate in Children with Influenza

“…We diagnosed the patients as having influenza A or B by using the diagnostic kit, but did not investigate the subtype or gene mutations of their viruses. For example, the H275Y mutation that is found in most influenza A/H1N1 cases and in a few percent of influenza A/H1N1pdm cases induces resistance to OT and Peramivir [11,12]. Because there was no report that more cases infected to be unsatisfactory in a large percentage of patients under the age of 6 years [6].…”