The FDA has approved a fifth vaccine for protection against the 2009 H1N1 influenza virus. The vaccine is manufactured by ID Biomedical Corp. of Quebec, Canada, owned by GlaxoSmithKline PLC. As with the four previous H1N1 influenza vaccines licensed by the FDA on Sept.15, 2009, ID Biomedical Corporation will manufacture its H1N1 vaccine using the established, licensed egg-based manufacturing process used for producing seasonal flu vaccine. Potential side effects of this H1N1 vaccine are expected to be similar to those of the seasonal and H1N1 flu vaccines. The most common side effect is soreness at the injection site. Others may include mild fever, body aches and fatigue for a few days after the inoculation. As with any medical product, unexpected or rare serious adverse events may occur. The FDA is collaborating with other government agencies to enhance adverse event safety monitoring during and after the H1N1 2009 vaccination program. ID Biomedical’s H1N1 monovalent vaccine will be produced in multi-dose vials, in a formulation that contains thimerosal.