There is evidence that helminth infections during pregnancy affect the immune system of the mother and the unborn child. As a consequence, the antimicrobial- immune and vaccine- response of the infant may be deficient. The aim of the present study is to measure the influence of maternal helminth infection (schistosomal, filarial and intestinal helminth infection) on vaccine immunogenicity of their infants. The main focus is on immune responses of infants to vaccine antigens given as part of the expanded program on immunization (EPI) in Gabon at an age when infants are unlikely to be infected with helminths and are immunologically primed by their intrauterine life. The objective is to investigate if and which species of helminths during pregnancy have an effect on any of the EPI vaccine-induced immune responses.