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

The new H1N1 influenza virus seen in 2009 has been designated a pandemic by the World Health Organization, due to the sustained community outbreaks seen in the United States and Mexico. Based on preliminary data, it appears children and young adults were particularly at risk of the H1N1 virus. People infected with HIV were also more susceptible to severe influenza infections than those who are uninfected. Children with HIV infection, then, have a compounded risk of H1N1 infection. Higher doses of influenza vaccines are associated with the development of higher levels of serum antibodies, which are needed to resist infection. Higher vaccine doses can be used to improve vaccine effectiveness in at-risk populations. This study tested the safety and immune response of HIV infected children and youth to a high dose of a vaccine for the new H1N1 influenza virus. Participation in this study lasted 7 months and had two steps. The first step involved receiving the first dose of H1N1 virus vaccine, and the second step, occurring 21 days later, involved receiving the second dose of vaccine. Each dose of vaccine was delivered via two intramuscular shots (four total injections). After receiving each dose of the vaccine, participants were given a diary to record any symptoms or reactions. Participants were stratified into three groups by age, including 4 to 9 years, 9 to 18 years, and 18 to 25 years. Participants completed five scheduled visits, taking place at screening, study entry, Days 21 and 31, and after 7 months. Measurements taken on these visits included a medical history, physical and neurological exams, a blood draw, and, when applicable, a pregnancy test. In addition to these visits, participants received up to three additional phone calls or visits occurring 2 and 10 days after the first dose of vaccine and 2 days after the second dose of vaccine to check for reactions to the vaccine.