United States health authorities warned the population that the current strain of flu circulating the country can resist the popular antiviral drug Tamiflu. Doctors are advised to add another drug or substitute Tamiflu with another drug in order to treat such cases.

The Centers for Disease Control and Prevention said that 49 out of 50 trials resisted Tamiflu. However, it can still be treated with other flu drugs. Tamiflu is not used in the majority of cases and for this reason the health authorities did not consider the case as a major threat.

The CDC recommends that the patients suspected of having the flu type known as influenza A H1N1 should receive GlaxoSmithKline PLC's Relenza antiviral drug or a combination of Roche Holding AG's Tamiflu and a generic drug called rimantadine.

"With the predominance of influenza A H1N1 viruses in the community, we felt compelled to at least alert physicians to the fact that these resistant viruses may be out there, and they may encounter them in practice," said Joseph Bresee with CDC's influenza division in Atlanta.

The other types of flu - influenza B and influenza A H3N2 - can still be treated with Tamiflu, which is the most attractive treatment because it is taken in a pill and children as young as 1 year old can receive it.

The current flu shot seems to get the jog done. The peak of the flu season is in February, so there is still plenty of time to get your flu shot.