Immunogenicity and safety of inactivated monovalent 2009 H1N1 influenza A vaccine in immunocompromised children and young adults

► In 2009, an H1N1 monovalent influenza vaccine was recommended in addition to the seasonal vaccine. ► We evaluated the immunogenicity and safety of H1N1 influenza vaccine in immunocompromised children. ► The H1N1 vaccine was safe and well tolerated in children with cancer, HIV, and sickle cell disease. ► The H1N1 vaccine resulted in an adequate immune response in children with sickle cell disease. ► The H1N1 vaccine was only modestly immunogenic in children with cancer or HIV infection.