Bacteriophage communities are a reservoir of unexplored microbial diversity in neonatal health and disease.

Acquisition and development of the gut microbiome are vital for immune education in neonates, especially those born preterm. As such, microbial communities have been extensively studied in the context of postnatal health and disease. Bacterial communities have been the focus of research in this area due to the relative ease of targeted bacterial sequencing and the availability of databases to align and validate sequencing data. Recent increases in high-throughput metagenomic sequencing accessibility have facilitated research to investigate bacteriophages within the context of neonatal gut microbial communities. Focusing on unexplored viral diversity, has identified novel bacteriophage species and previously uncharacterised viral diversity. In doing so, studies have highlighted links between bacteriophages and bacterial community structure in the context of health and disease. However, much remains unknown about the complex relationships between bacteriophages, the bacteria they infect and their human host. With a particular focus on preterm infants, this review highlights opportunities to explore the influence of bacteriophages on developing microbial communities and the tripartite relationships between bacteriophages, bacteria and the neonatal human host. We suggest a focus on expanding collections of isolated bacteriophages that will further our understanding of the growing numbers of bacteriophages identified in metagenomes.