Neonatal immunization: where do we stand?

Abstract

Recognition of the high burden of disease in early life and advances in the understanding of neonatal immunology have resulted in renewed interest in maternal and neonatal vaccination. This article reviews existing information and recent advances in neonatal human immunization. Recent findings have demonstrated the neonatal immune system not to be immature but rather specifically adapted for early postnatal life. This includes the preferential induction of memory B cell rather than antibody-secreting plasma cells and polarization of neonatal T-cell responses away from potentially deleterious T-helper type 1 cytokines. Recent neonatal acellular pertussis and pneumococcal conjugate vaccine trials have proven that a birth dose of acellular pertussis and/or pneumococcal vaccine, in limited samples sizes, are well tolerated and immunogenic; however they have identified vaccine interference as a critical issue to address. Neonatal immunization may be a well tolerated and effective preventive strategy against early life pathogens. Research to better understand how neonatal vaccine responses are elicited and to identify optimal early life adjuvants and formulations may broaden neonatally vaccine-preventable diseases to pertussis, rotavirus and possibly influenza, further reducing disease burden in this vulnerable group. Hurdles to neonatal vaccination include safety concerns, both immunological and clinical, demonstration of vaccine efficacy and public acceptance.