Between 2000 and 2019, the Stanford Healthcare Clinical Virology Laboratory performed HIV-1 resistance testing for 9199 individuals in Northern California. Nonsubtype B viruses were identified in 3. 5%, most often CRF01AE (1. 0%), subtype C (1. 0%), CRF02AG (0. 46%), and subtype A (0. 45%). Non-B viruses, particularly CRF01AE and CRF02AG, increased significantly over time. Although subtype B remained dominant, the rising presence of non-B subtypes reflects growing viral diversity within the U. S. epidemic.
Tao et al. (Wed,) studied this question.