 In December 2012 , 2010 , the World Health Organization ( WHO ) reported 314 samples of the 2009 pandemic H1N1 flu tested worldwide have shown resistance to oseltamivir ( Tamiflu ) . This is not totally unexpected as 99 @.@ 6 % of the seasonal H1N1 flu strains tested have developed resistance to oseltamivir . No circulating flu has yet shown any resistance to zanamivir ( Relenza ) , the other available anti @-@ viral . 
