Many clinics in metropolitan cities across Europe now routinely report 25 to 40% of their patient profile as having non-B clade virus, including London-based hospitals.

It is currently estimated that one quarter of HIV-infected people in the United Kingdom have contracted a non-B subtype. Such infections are found almost exclusively among people who have contracted HIV through heterosexual sex. A British study of over 600 people born in the United Kingdom or Europe found that 14% of the men and 35% of the women were infected with non-B subtypes^[1].

Due to the preponderance of the B subtype in western countries, resistance research has focused on the evolution and mutations associated with the B subtype. Little is known about how drug resistance may evolve differently in people infected with non-B subtypes, although this is a growing area of interest.

There is increasing recognition of the impact subtype has on pathways to resistance during anti-HIV treatment. There is also recognition of the need for further research in non-B subtypes to inform the treatment decisions of people with non-B subtypes and the analysis of their resistance assays.