While regulatory endpoints for pneumococcal conjugate vaccines (PCVs) routinely include radiologically- or vaccine serotype (VST) confirmed disease, public health decision-making benefits from consideration of all disease prevented regardless of diagnostic or etiological confirmation.
We followed PRISMA guidelines to perform a systematic literature review for Phase III/IV efficacy trials of PCVs from 1997 through 2019. We estimated study-specific vaccine-preventable disease incidence (VPDI) (control group minus intervention group incidences) for all-cause disease versus radiologically- and/or etiologically-confirmed outcomes. VPDI ratios between the broadest clinical and most narrowly defined outcomes were calculated [PROSPERO registration, CRD42019145268].
Ten studies met the criteria. In children < 5 years, VPDI ratios ranged from 0.6 to 3.7 for otitis media (clinical versus VST etiologically-confirmed); from 1.3 to 1.8 for pneumonia (clinical versus radiologically-confirmed); 3.1 and 19.0 for pneumonia (clinical versus bacterial or VST); and 3.8 in one study of invasive pneumococcal disease (non-laboratory to laboratory-confirmed). In adults, VPDI ratios ranged from 2.2 to 2.9 for pneumonia (clinical to pneumococcal or VST).
Relying on only radiologically-confirmed or etiologically-confirmed outcomes substantially underestimated PCVs’ public health benefits. Broader clinical outcomes should be considered by vaccine technical committees when making decisions for pediatric and adult PCV use.