Seroincidence of 2009 H1N1 infection in HIV-infected and HIV-uninfected women prior to vaccine availability.

The 2009 H1N1 pandemic was a unique opportunity to investigate differences in influenza infection using serology by HIV status. Using serial serum specimens collected from 1 April to 30 September 2009 and the prior 2 years from Women's Interagency HIV study participants, there was no difference in serologic evidence of 2009 H1N1 infection among HIV-infected women with a CD4 cell count at least 350 cells/μl compared with HIV-uninfected women. Owing to evidence showing a greater risk of influenza-related complications, HIV-infected individuals should continue to be a priority group for vaccination.