Influenza A among patients with human immunodeficiency virus: an outbreak of infection at a residential facility in New York City.

Although annual influenza vaccination is recommended for persons who are infected with human immunodeficiency virus (HIV), data are limited regarding the epidemiology of influenza or the effectiveness of influenza vaccination in this population. We investigated a 1996 outbreak of infection with influenza A at a residential facility for persons with AIDS. We interviewed 118 residents and employees, reviewed 65 resident medical records, and collected serum samples for measurement of influenza antibody titers. After controlling for history of smoking, influenza vaccination, and resident or employee status, in a multivariate model, HIV infection was not statistically associated with influenza-like illness (ILI). Symptoms and duration of ILI were similar for most HIV-infected and HIV-uninfected persons. However, 8 (21.1%) of 38 HIV-infected persons with ILI (vs. none of 15 HIV-uninfected persons) were either hospitalized, evaluated in an emergency room, or had ILI lasting > or = 14 days (P=.06). Vaccination effectiveness (VE) was similar for HIV-infected and HIV-uninfected persons. Vaccination was most effective among HIV-infected persons with CD4 cell counts of >100 cells/microL (VE, 65%; 95% CI, 36%--81%) or HIV type 1 virus load of <30,000 copies/mL (VE, 52%; 95% CI, 11%--75%). Providers should continue to offer influenza vaccination to HIV-infected persons.