Changing patterns in HIV‐1 non‐B clade prevalence and diversity in Italy over three decades

Background HIV‐1 non‐B subtypes have recently entered Western Europe following immigration from other regions. The distribution of non‐B clades and their association with demographic factors, over the entire course of the HIV‐1 epidemic, have not been fully investigated in Italy. Methods We carried out a phylogenetic analysis of HIV‐1 pol sequences derived from 3670 patients followed at 50 Italian clinical centres over nearly three decades. Results Overall, 417 patients (11.4%) carried non‐B subtypes. The prevalence of non‐B strains increased from 2.6% in 1980–1992 to 18.9% in 1993–2008 (P