Prematurity as a secondary immunodeficiency disorder with increased risk of infections: A mini-review

*1Ibraheem, R. M., and 2Issa, A.

1Department of Paediatrics and Child Health, University of Ilorin and University of Ilorin Teaching Hospital, PMB 1515, Ilorin, Nigeria

2Department of Paediatrics, Children Specialist Hospital, Ilorin, Nigeria

*Correspondence to:; +2348033704168; ORCID: 0000-0002-3960-9740

Prematurity significantly increases neonatal mortality in sub-Saharan Africa. Underdeveloped immune systems and prolonged hospitalization elevate the risk of secondary immunodeficiency leading to heightened vulnerability to healthcare-associated infections, including neonatal sepsis from various sources like intrauterine, intrapartum, and postnatal agents. This review explores the impact of prematurity on infection susceptibility and the role of immature immunity. A literature search using PubMed and Google Scholar identified relevant articles published between January 1980 and December 2022, focusing on terms such as “preterm,” “prematurity,” “neonatal sepsis,” and “secondary immunodeficiency.” Despite neonatal susceptibility to sepsis, accurate incidence estimates are lacking in many countries, and preterm infants face higher morbidity and mortality risks compared to full-term babies. Early-onset infections usually manifest within the first 72 hours post-delivery, while late-onset neonatal sepsis occurs after this period. Immaturity affects various immune system components, with gestational age influencing functionality. The compromised innate immune response in preterm infants involves factors such as fragile skin, reduced tear/mucus production, and low antimicrobial peptide levels. Complement deficiencies and impaired neutrophil function increase susceptibility to infections. Macrophages, dendritic cells, and natural killer cells exhibit reduced activity, impacting viral clearance. Preterm infants also have lower immunoglobulin (Ig) G levels, contributing to a weakened adaptive immune response. Hypogammaglobulinaemia heightens susceptibility to infections relying on antibody-mediated protection, while low secretory IgA production and delayed antibody response predispose to gastrointestinal and respiratory infections. The combined effect of immature immunity and medical interventions heightens preterm infants’ susceptibility to pathogens. Recommendations for mitigating infection risks include antimicrobial stewardship, prompt initiation of exclusive breastfeeding, and timely administration of routine vaccinations.

Keywords: Secondary immunodeficiency, Preterms, Innate,Adaptive, Neonatal, sepsis

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Prematurity as a secondary immunodeficiency disorder with increased risk of infections: A mini-review