Influenza A Responds to Tamiflu® Better Than Influenza B
Influenza A Responds to Tamiflu® Better Than Influenza B
Special Report
By Carol A. Kemper, MD, FACP, Clinical Associate Professor of Medicine, Stanford University, Division of Infectious Diseases, Santa Clara Valley Medical Center. Dr. Kemper reports no financial relationship relevant to this field of study.
Source: Kawai N, et al. Clin Infect Dis. 2006:43:439–444.
To evaluate the effectiveness of oseltamivir for influenza, it was administered to 1818 patients with Influenza A and 1485 patients with Influenza B, all of whom were being seen in an "usual clinical setting" in 9 different community clinics in Japan. The patients were grouped by age and by time of onset of fever to the time of administration of the first dose of oseltamivir. A small number of patients who did not take the drug was used as a comparator group.
Not surprisingly, patients who received no treatment had a significantly longer duration of fever compared with treated patients with Influenza A (82 hrs vs 48 hrs) or Influenza B (78 hrs vs 65 hrs, respectively) (both groups, P < 0.001). The duration of fever after receipt of the drug was similar regardless of age or the timing of the first dose of drug, with one exception. Patients aged 7–15 years had a somewhat shorter duration of illness, although this difference was arguably not clinically significant (~4 hrs).
What was somewhat surprising was the finding that for those who received treatment, the duration of fever following administration of oseltamivir was significantly shorter for patients with Influenza A compared to those with Influenza B. This statistically significant difference was found for all age groups, regardless of the timing of administration. For example, comparing patients with Influenza A or B, the mean duration of fever after receipt of thefirst dose of oseltamivir was 32 hrs vs 48 hrs, respectively, for those who received the drug within 0–12 hrs. Similarly, the mean duration of fever after the 1st dose of oseltamivir in patients with Influenza A vs Influenza B was 32 hrs and 45 hrs, respectively, for those who received the drug within 27–48 hrs of onset of symptoms.
In addition, isolation of virus at the completion of treatment was significantly more frequent in patients with Influenza B than Influenza A (52% vs 16%, P < 0.001).
These data confirm that oseltamivir is more effective against infection with Influenza A vs Influenza B, although the difference may not be especially clinically meaningful.
To evaluate the effectiveness of oseltamivir for influenza, it was administered to 1818 patients with Influenza A and 1485 patients with Influenza B, all of whom were being seen in an "usual clinical setting" in 9 different community clinics in Japan.Subscribe Now for Access
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