Second-line antiretroviral therapy in resource-limited settings: what we know and the challenges of ever-changing antiretroviral therapy

Almost 22 million persons with human immunodeficiency virus (HIV) are receiving antiretroviral therapy (ART) with the majority living in resource-limited settings (RLS) (1). This remarkable achievement owes much of its success to the public health approach adopted by the World Health Organization (WHO) (2).