The study assessed the impact of oral HIV pre-exposure prophylaxis (PrEP) in British Columbia (BC) from 2018 to 2022 on drug resistance and HIV transmission in phylogenetic clusters. She found that newly diagnosed PrEP users were more likely to be part of phylogenetic clusters and more often had reverse transcriptase inhibitor (NRTI) resistance mutations, specifically the M184I/V mutation. Simulations showed that PrEP averted around 20 new HIV cases per year, mainly in groups of men who have sex with men (GBM). Most of the averted diagnoses were recorded in large and medium-sized clusters, while smaller clusters with a higher average age and lower proportion of PrEP users had fewer averted cases. PrEP has rarely contributed to underlying drug resistance, particularly with incomplete adherence or when prescribed during an acute infection. The results confirm the high efficacy of PrEP in HIV prevention and highlight the need for a targeted service for different subpopulations. The interpretation of the results is limited by the incomplete sampling and assumptions of the simulation models.