In conclusion, the stable evolution of 2009 H1N1pdm offers an opportunity to control its spread and prevent infections. Reports about new mutations, however, will still be important if those changes can confer an enhanced transmissibility or resistance to drugs. Furthermore, a continuous surveillance by public health authorities will be critical to monitor the appearance of new influenza variants, especially in animal reservoirs such as swine and birds, in order to prevent the potential animal-human transmission of viruses with pandemic potential.