Evaluation of effectiveness of the 23-valent pneumococcal capsular polysaccharide vaccine for HIV-infected patients

Background: We conducted a retrospective case-control study to evaluate effectiveness of pneumococcal vaccine against invasive disease among adults with human immunodeficiency virus (HIV) infection in San Francisco, Calif, and Atlanta, Ga. Methods: Case patients were 18- to 55-year-old subjects with HIV infection who were admitted to selected hospitals in Atlanta or San Francisco from February 1992 to April 1995 from whom Streptococcus pneumoniae was isolated from a normally sterile site. Controls were HIV-infected patients of similar age matched to cases by hospital of admission and CD4 lymphocyte count (<0.20, 0.20-0.499, greater than or equal to 0.50 x 10(degrees)/L [<200, 200-499, greater than or equal to 500 cells/ mm(3)]) or clinical stage of acquired immunodeficiency syndrome. Case and control subjects were restricted to per sons known to have HIV infection before hospital admission. Analysis used matched univariate and conditional logistic regression. Results: One hundred seventy-six case patients and 327 controls were enrolled. By univariate analysis, persons with pneumococcal disease were more likely to be black, be current smokers, and have close contact with children. Adjusted for these factors and CD4 cell count, pneumococcal vaccine effectiveness was 49% (95% confidence interval [CI], 12%-70%). Adjusting for all variables and key interaction terms, vaccine effectiveness among whites was 76% (95% CI, 35%-91%), whereas effectiveness among blacks was 24% (95% CI, -50% to 61%). Among controls, vaccination was significantly less common among blacks (29% vs 45%; P<.005). Conclusions: Pneumococcal vaccine demonstrated protection against invasive pneumococcal infections among white but not black HIV-infected adults. Failure to demonstrate effectiveness among blacks may be due to limited power because of low use of the vaccine in this population, immunization at more advanced stages of immunosuppression, or unmeasured factors. These data support current recommendations for use of pneumococcal vaccine in HIV-infected persons and highlight a clear need for strategies to improve vaccine-induced protection.