Background: Immunization with 23-valent pneumococcal polysaccharide vaccine (PPV) may increase incidence of pneumonia in HIV-1-infected patients (pts) not receiving HAART in Africa.

Methods: Pts receiving and not receiving 23-valent PPV were prospectively observed for changes of CD4⁺ and PVL at wk 4 of vaccination and at the end of study and development of pneumococcal disease (PD), all causes of community-acquired pneumonia (CAP) and new AIDS-defining opportunistic illness (OI), and mortality at NTUH in Taiwan between June 1, 2000 and September 30, 2002. The Cox-proportional hazards model was used to assess the impact of the pneumococcal vaccination with and without adjustment for age, sex, risk behavior for HIV transmission, baseline CD4⁺ count, PVL, baseline OI, and use of HAART. Odds ratios and 95% confidence intervals (95% CI) were also calculated for risk analyses. All tests were two-tailed. A p value < 0.05 was considered significant.

Results: A total of 305 HIV-1 infected pts received PPV and 98.2% received HAART whose median baseline CD4⁺ count and PVL were 0.179 x 10⁹/L and 3,850 copies/ml, respectively. 203 patients, 84.2% receiving HAART, did not receive PPV and their median baseline CD4⁺ count was 0.195 x 10⁹/L and PVL 42,900 copies/ml. The incidence of PD among vaccinees was 2.2 per 1,000 PY over the median observation of 641 days while that for non-vaccinees was 22.9 per 1,000 pt years over the observation of 500 days (p = 0.007). The adjusted odds ratio (AOR) for developing PD of vaccinees as compared to non-vaccinees was 0.081 (95% CI, 0.009–0.724; p = 0.02). The median CD4+ count increased by 0.045 x 10⁹/L and PVL decreased by 130 copies/ml after one month of pneumococcal vaccination among the selected 31 vaccinees. The AOR of developing all cause CAP and new OI of vaccinees as compared to non-vaccinees was 1.393 (95% CI, 0.478–4.059, p = 0.54) and 1.074 (95% CI, 0.310–3.716, p = 0.91), respectively. AOR for death of vaccinees as compared to non-vaccinees was 0.144 (95% CI, 0.041–0.505, p = 0.002).

Conclusions: Our data indicated that immunization with 23-valent PPV reduced risk for PD and death among HIV-1-infected pts who were treated with HAART. Vaccination did not increase PVL or the risks for developing all cause CAP and HIV progression.