Researchers in Japan have detected a drug-resistant form of flu among patients in a small study in Japan, thus raising concerns that flu viruses are developing resistance to oseltamivir (or Tamiflu) and are spreading from human-to-human.

Few patients in Japan, who had type B influenza, normally a milder flu causing smaller outbreaks than the more common type A, showed signs of resistance to the drugs Tamiflu and Relenza. It also worries doctors who now say they would need to find new medicines to treat drug-resistant flu if the viruses start spreading

GlaxoSmithKline Plc's prescription drug, Relenza, is now approved to prevent influenza in adults and children ages 5 and older.

According to Reuters, Relenza joins Roche AG's Tamiflu as the only other drug with Food and Drug Administration clearance for both prevention and treatment of the flu

With flu season reaching its peak, two drugs typically prescribed to fight the virus will be ineffective this season and should not be prescribed, the Centers for Disease Control and Prevention announced Saturday.

The CDC found in tests that the antiviral drugs amantadine and rimantadine were ineffective 91 percent of the time against H3N2 influenza, the dominant strain this season. However, two other antiviral drugs, Tamiflu and Relenza are still effective, says CDC Director Dr. Julie Gerberding. Amantadine and rimantadine are older, less expensive and less commonly prescribed drugs

The Centers for Disease control issued a warning to doctors that two commonly-used drugs prescribed to fight influenza should no longer be used, as the primary strain of the virus has built up resistance to the drugs.

According to the CDC, 91 percent of the samples test proved resistant to rimantadine and amantadine, up last year from only 11 percent

The Health and Human Services Secretary says Sunday the U.S. is unprepared for the next flu pandemic, as it lacks the capability of providing 300 million doses of a vaccine for three to five more years.

"What we all learned from (Hurricane) Katrina is that sometimes we have to think very clearly about the unthinkable," says Mike Leavitt. "We're not as prepared as we need to be. ...We will not have enough for everyone