Diagram of influenza virus nomenclature. Image source: Wikipedia, GNU Free Documentation License.
Virtually all cases of influenza circulating in the United States now resist the main drug (Tamiflu) used to treat it.
98 percent of all flu samples from the H1N1 strain were resistant to Tamiflu. Last flu season, only 19 percent of H1N1 viruses were Tamiflu (oseltamivir)-resistant.
Oseltamivir. Image source: Wikipedia, public domain.
In February 2006, the US Centers for Disease Control and Prevention (CDC) reported that 92.3% of the circulating influenza A(H3N2) at that time was resistant to the adamantanes (amantadine and ramantidine).
What to do?
Treatment that is still effective against influenza is inhaled Relenza (Zanamivir). Your best option is still receiving the annual flu vaccine.
Zanamivir. Image source: Wikipedia, GNU Free Documentation License.
The traditional flu shot, given as an injection in the arm, performs better than the newer nasal spray flu vaccine.
Resistance to flu drug widespread in U.S. Reuters.
Flu Shot Beats Nasal Spray Flu Vaccine? WebMD Health News.
Infections With Oseltamivir-Resistant Influenza A(H1N1) Virus in the United States. Nila J. Dharan, MD; Larisa V. Gubareva, PhD; John J. Meyer, MPH; Margaret Okomo-Adhiambo, PhD; Reginald C. McClinton, MPH; Steven A. Marshall, MS; Kirsten St. George, MAppSc, PhD; Scott Epperson, MPH; Lynnette Brammer, MPH; Alexander I. Klimov, PhD; Joseph S. Bresee, MD; Alicia M. Fry, MD, MPH; for the Oseltamivir-Resistance Working Group. JAMA. 2009;301(10):(doi:10.1001/jama.2009.294).
Morbidity and Mortality Associated With Nosocomial Transmission of Oseltamivir-Resistant Influenza A(H1N1) Virus. Jairo Gooskens, MD; Marcel Jonges, MSc; Eric C. J. Claas, PhD; Adam Meijer, PhD; Peterhans J. van den Broek, MD, PhD; Aloys C. M. Kroes, MD, PhD. JAMA. 2009;301(10):(doi:10.1001/jama.2009.297).
Live Attenuated or Inactivated Influenza Vaccines and Medical Encounters for Respiratory Illnesses Among US Military Personnel. Zhong Wang, PhD, MPH; Steven Tobler, MD, MPH; Jean Roayaei, PhD; Angelia Eick, PhD, ScM. JAMA. 2009;301(9):(doi:10.1001/jama.2009.265).
The Evolution of Influenza Resistance and Treatment. David M. Weinstock, MD; Gianna Zuccotti, MD. JAMA. 2009;301(10):(doi:10.1001/jama.2009.324).
Global Transmission of Oseltamivir-Resistant Influenza. NEJM, 2009.