But during the 2007-2008 flu season last year, the Tamiflu-resistant strain of the virus accounted for fully one in five cases of flu in the United States. A report in the Journal of the American Medical Association (JAMA) found that the H1N1 subtype of influenza A viruses commonly proved resistant to the popular drug oseltamivir. Report Granthem € A virulent strain of influenza sowing misery across the United States is proving resistant to what had been until recently the most effective anti-viral drugs, according to a study released Monday. Data last year for 99 individuals infected with oseltamivir-resistant influenza found that five of the patients had to be hospitalized, four of whom died. Oseltamivir, sold commercially in the United States as the drug Tamiflu, is produced by Swiss pharmaceutical giant Roche, and is the main antiviral remedy on the market.

Equally worrying is the virulence of this particular strain of flu. Preliminary data during the current 2008-2009 influenza season shows that the virus's resistance to the Tamiflu continues to be high and that the drug-resistant strain of the flu continue to have a high incidence. The authors wrote that the worrisome development "has highlighted the need for the development of new antiviral drugs and rapid diagnostic.

Flu strain proves resistant to medication.