No Signs of Epidemic in Current Influenza Season
Nearly all influenza A strains resistant to oseltamivir
MONDAY, Feb. 16 (HealthDay News) -- The mortality rate due to pneumonia or influenza is below the epidemic threshold for the flu season so far, according to a report published in the Feb. 13 issue of the U.S. Centers for Disease Control and Prevention's Morbidity and Mortality Weekly Report.
Lynette Brammer, of the CDC's National Center for Immunization and Respiratory Diseases in Atlanta, and colleagues report that 81,842 respiratory samples were tested for influenza virus in the United States from Sept. 28, 2008 to Jan. 31, 2009, and that 4,336 (5.3 percent) of them tested positive for the virus, including 3,641 (84 percent) that were influenza A viruses and 695 (16 percent) that were influenza B viruses. The predominant virus strains are antigenically related to those in the season's vaccine, the authors note.
The CDC tested 308 influenza viruses to detect resistance to adamantanes and neuraminidase inhibitors, and found that 185 (97.4 percent) out of 190 influenza A viruses tested were resistant to oseltamivir but all were susceptible to zanamivir, while all 77 influenza B viruses tested were susceptible to both neuraminidase inhibitors, the investigators report.
"Since September 28, 2008, the weekly percentage of deaths attributed to pneumonia and influenza ranged from 6 percent to 7.5 percent, remaining below the epidemic threshold," the authors write.