Incidence of invasive pneumococcal disease among individuals with sickle cell disease before and after the introduction of the pneumococcal conjugate vaccine.

BACKGROUND: We sought to determine the incidence of invasive pneumococcal disease (IPD) among individuals with sickle cell disease (SCD) before and after the introduction of the pneumococcal conjugate vaccine (PCV). METHODS: Individuals with SCD who were enrolled in Tennessee Medicaid from January 1995 through December 2004 were identified using SCD-specific International Classification of Diseases, Ninth Revision, Clinical Modification codes. Population-based surveillance data were used to identify individuals with IPD and were linked to patients with SCD in the Tennessee Medicaid database to determine incidence rates of IPD. Clinical data were collected on all subjects with IPD, and antibiotic susceptibility testing and serotyping were performed on all available pneumococcal isolates. RESULTS: We identified 2026 individuals with SCD, who constituted 13,687 person-years of follow-up. During the study period, 37 individuals with SCD developed IPD, and 21 of these patients were aged <5 years. In a comparison of the pre-PCV period (1995-1999) with the post-PCV period (2001-2004), the rate of IPD decreased by 90.8% in children aged <2 years (from 3630 to 335 cases per 100,000 person-years; P<.001) and by 93.4% in children aged <5 years (from 2044 to 134 cases per 100,000 person-years; P<.001). Rates of IPD for patients with SCD who were aged >or=5 years decreased from 161 cases per 100,000 person-years during the pre-PCV period to 99 cases per 100,000 person-years during the post-PCV period (P=.36). CONCLUSION: The rate of IPD among children with SCD who are aged <5 years has decreased markedly since the introduction of routine administration of PCV to young children.

Cardiopulmonary hospitalizations during influenza season in adults and adolescents with advanced HIV infection.

The etiologic role of influenza in hospitalizations and deaths among persons infected with HIV since the introduction of highly active antiretroviral therapy (HAART) is not known. A retrospective cohort study was performed of all persons aged 15 to 50 years with AIDS or advanced HIV infection enrolled in the Tennessee Medicaid program from 1995 through 1999, representing 7368 person-years of follow-up. The influenza season was defined based on local virus surveillance, and hospitalizations were measured for acute cardiopulmonary causes and deaths from any cause throughout the year. From 1995 through 1999, cardiopulmonary hospitalization rates in HIV-infected patients declined by 53% and death rates declined by 77%. The influenza-attributable hospitalization rate was 48 (95% confidence interval [CI]: 16-91) per 1000 persons in 1995 and 5 (95% CI: -0.5-11) per 1000 persons per year during 1996 through 1999, after the introduction of HAART. Influenza-associated hospitalizations have declined in patients with HIV infection in the post-HAART era. Rates remain comparable to rates in other high-risk groups for which annual influenza vaccination is recommended, however.