Exploring the evidence behind the comparable impact of the pneumococcal conjugate vaccines PHiD-CV and PCV13 on overall pneumococcal disease

Abstract

The worldwide implementation of pneumococcal conjugate vaccines (PCVs) in children has reduced the overall pneumococcal disease burden. Two PCVs are widely available for infant vaccination: the pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) and the 13-valent PCV (PCV13). While these PCVs differ in serotype composition (PCV13 includes polysaccharides of serotypes 3, 6A and 19A; PHiD-CV does not), their impact on the overall pneumococcal disease burden in children is comparable. This commentary summarizes the evidence of comparability between PHiD-CV and PCV13 and explores why differences in serotype composition may not necessarily translate into a differential clinical impact. Both vaccines confer similarly high protection against disease caused by vaccine serotypes and lead to a partial replacement by non-vaccine serotypes. PHiD-CV does not protect against serotype 3 disease (not included in the vaccine) and PCV13’s effect on this serotype has been inconsistent. PHiD-CV provides some cross-protection against disease caused by vaccine-related serotype 19A but neither vaccine has fully controlled 19A disease. While protection against 19A is higher for PCV13 than PHiD-CV, replacement by non-PCV13 serotypes in settings with a PCV13 program appears to compensate for this difference. This results in a similar residual overall disease burden with both vaccines.

Vaccination against Streptococcus pneumoniae in Children Born between 2015 and 2018 in Poland—How Has the Introduction of Free Compulsory Pneumococcal Vaccination Affected Its Uptake?

“…Data from European countries show that the introduction of mandatory pneumococcal vaccination has reduced the incidence of IPD. This effect was demonstrated for both PCV10 and PCV13 [50,51]. The difference is seen in the case of serotypes 6C and 19A, where PCV10 offers no significant protection.…”

Predicted serotype distribution in invasive pneumococcal disease (IPD) among children less than five years prior to the introduction of the Pneumococcal Conjugate Vaccine (PCV) in Nigeria

“…Although this may indicate that PCV13 may provide better protection, empirical data has shown that PCV13 has little to no protection against serotype 3 and has similar levels of serotype replacement as PCV10. (39,40) This higher predictions in serotype coverage for PCV13 may therefore not translate to larger IPD reductions. Our predictions show that SII-PCV has similar coverage to PCV10, and we attribute this to differences in carriage prevalence and IC of the included and excluded serotypes.…”