Safety of and Immune Response to an H1N1 Influenza Virus Vaccine in HIV Infected Children and Youth

Inclusion Criteria for Step I: * HIV infected * HIV-1 was perinatally acquired, in the opinion of the investigator * Participants receiving antiretrovirals (ARVs) must have been receiving a stable regimen for 90 days prior to entry with no intention to modify their regimen within 60 days following study entry * Participants not receiving ARVs at entry must not have received ARVs within 90 days prior to entry and must NOT plan to initiate ARVs within 60 days following study entry * Ability to complete all study immunizations and evaluations, in the opinion of the investigator * Agrees to use contraception, if necessary * Documented platelet count of more than 50,000 per mm3 and an absolute neutrophil count (ANC) of more than 500 per mm3 within the 30 days prior to study entry * Youth of legal age (from 18 to 25 years of age), parent or legal guardian, or participants who are emancipated minors must provide informed consent Inclusion Criteria for Step II: * Received the first dose of Influenza A (H1N1) 2009 monovalent vaccine at least 21 days ago * Documented platelet count of more than 50,000 per mm3 and an ANC of more than 500 per mm3 within the 30 days prior to Step II entry * If a woman became pregnant after Dose #1, she must be at more than 14 weeks of gestation and have her obstetrician's permission to receive the vaccine Exclusion Criteria for Step I: * Pregnancy * Known allergy to egg protein (egg or egg product) or other components in the vaccines (these may inclu…