De fleste data har indikeret, at et lille antal spædbørn opnåede antistofkoncentrationer ≥ 0, 35 µg/ ml (den af WHO anbefalede antistofkoncentration) 1 mod serotyperne 6B og 23F efter en serie med to doser primærvaccination, når der sammenlignes direkte eller indirekte med serier bestående af tre doser primærvaccination.
Most of the data have indicated that smaller proportions of infants achieved antibody concentrations ≥ 0.35 μ g/ mL (the reference antibody concentration recommended by WHO) 2 against serotypes 6B and 23F after two-dose primary series when directly or indirectly compared with three-dose primary series.