Background: Pneumococcal prime-boost vaccination is recommended for solid organ transplant recipients, but is not thoroughly tested in this population. Furthermore, a pneumococcal vaccine dose effect has never been investigated, though observed in healthy adults. To assess whether a double dose of 13-valent pneumococcal conjugate vaccine (PCV13) and of 23-valent pneumococcal polysaccharide vaccine (PPV23) increases the immunogenicity of prime-boost vaccination in kidney transplant recipients (KTRs) and patients on the kidney transplant waiting list (WLPs), a phase 3, randomized, non-blinded trial was conducted.
Methods: KTRs and WLPs were in parallel groups assigned either normal or double dosage of both vaccines 12 weeks apart. A 'protective response' was an average geometric mean concentration ≥ 1 mg/L based on 12 vaccine shared serotype-specific IgG antibodies. Furthermore, number of antibodies with ≥ 2-fold rises and individual serotype-specific antibody concentrations were evaluated. Follow-up was 48 weeks.
Results: Seventy-four KTRs and 65 WLPs were enrolled. In WLPs, double dosage resulted in a significantly higher proportion of participants with a 'protective response' (66.7%), 5 weeks after PPV23, compared to normal dosage (35.5%), p = 0.015. KTRs exhibited no dose effect. After PPV23, all four groups had increased their number of serotypes with ≥ 2-fold rises (p ≤ 0.05 for both WLPs groups; p ≤ 0.01 for both KTRs groups). Vaccines were safe, well tolerated and still immunogenic at week 48.
Conclusions: Data suggests that double dosage of pneumococcal vaccines used according to the prime-boost strategy might be recommendable for WLPs. Furthermore, our data supports PPV23́s additive effect to PCV13 in KTRs and WLPs. (EudraCT: 2016-004123-23).
Keywords: Adults; Immunogenicity; Kidney transplant recipient; Pneumococcal conjugate vaccine; Pneumococcal polysaccharide vaccine.
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