Invasive pneumococcal disease remains a significant cause of morbidity and mortality in HIV-infected adults. PPV23 has been shown to have suboptimal immunogenicity in this group. Strategies such as priming with PCV13 followed by boosting with PPV23 may augment immune response. This single-centre randomised controlled trial assessed immunological efficacy of PCV13 followed by PPV 23 at 4 weeks versus PPV 23 alone in HIV-infected adults.
HIV-infected adults >18 years with no prior history of pneumococcal vaccination with a CD4 count > 200 cells/mm3were randomised to receive PCV13 at week 0 followed by PPV23 at week 4 (“prime boost/PB” group, n=27) or PPV 23 alone at week 4 (“unprimed” group, n=33). Quantitative antibody titres for 12 pneumococcal polysaccharide serotypes (PPS) (1, 3, 4, 5, 6B, 7F, 9V, 14,18C, 19A, 19F, 23F) shared by both vaccines were measured at weeks 0, 8 and 28.
Proportion of responders (>2-fold increase in antibody titre to > 6 vaccine serotypes) and fold increase in PPS IgG geometric mean titre (GMT) were compared. Wilcoxon, Student's/x2 tests were used to compare IgG levels and categorical variables as appropriate.
60 patients (mean age [SD] 37  years, 92% male, mean CD4 count 503  cells/mm3, 47% on HAART, mean HIV RNA 4.5log10 copies/ml) were enrolled. Baseline characteristics were well matched between groups.
Week 8 vaccine response rate was 88% and 86% in the PB and unprimed group respectively (p=1). Week 8 fold increase in GMT was greater in the PB group (mean [SD] 8.69 [4.61] vs. 4.49 [1.24], p<0.001) with significantly higher GMTs for serotype 23F (3.20 vs. 0.52ug/ml, p=0.0038).
At week 28, proportion of responders was significantly higher in the PB group (85% vs. 52%, p<0.01). Week 28 GMT in the PB group was significantly higher for 4 serotypes; 1 (0.48 vs0.29ug/ml, p=0.05), 4 (0.83 vs. 0.42ug/ml, p=0.023), 19F (1.51 vs. 0.88ug/ml p=0.04), 23F (1.54 vs. 0.42ug/ml, p=0.013) and fold increase in GMT remained greater in the PB group (4.39 [1.77] vs.2.47 [0.67], p=0.05).
The immunogenicity and durability of pneumococcal vaccine response in this study was enhanced by the prime boost strategy. This adds to evidence supporting recent changes in US pneumococcal vaccination recommendations and strengthens the call to review current pneumococcal vaccination guidelines in HIV-infected adults in Europe.
C. Rock, None
A. Brown, None
S. O'Dea, None
J. Dunne, None
C. Feighery, None
C. Bergin, None