HIV drug resistance refers to the ability of the virus to withstand the effect of a given antiretroviral drug to prevent its replication. Resistant HIV strains either emerge de novo in conditions of suboptimal drug levels by residual viral replication (acquired drug resistance) or they are transmitted to previously uninfected people (transmitted drug resistance). Transmitted resistance can limit therapeutic options for new patients and affect virological and immunological response to first line antiretroviral treatment.1 The World Health Organization recommends that countries establish surveillance systems for assessing transmitted and acquired resistance.2 3

In a linked research paper, the UK Collaborative Group on HIV Drug Resistance (doi:10.1136/bmj.e5253) examined the evolution of HIV drug resistance in the United Kingdom in treatment naive patients infected with virus subtype B.4 They found that the overall prevalence of drug resistance decreased between 2002 and 2007, from 15.5% to 9.6%, followed by a non-significant increase in prevalence to 10.9% in 2009. These are important findings because they suggest that antiretroviral regimens currently in use in the UK remain effective for most people …