Hunt GM, Ledwaba J, Salimo A, et al. - Using three nationally representative studies that assessed the effectiveness of national programs to prevent mother-to-child transmission of HIV (PMTCT), the prevalence of HIV drug resistance patterns amongst HIV infected infants was tracked. The first study was performed in 2010 (under the dual therapy PMTCT policy), the second from 2011 to 12 (PMTCT Option A policy) and the third from 2012 to 13 (PMTCT Option A policy). From 2010 to 2013, researchers observed an increase in infant non-nucleoside reverse transcriptase inhibitor (NNRTI) exposure from a single dose to daily throughout breastfeeding and an increase in maternal nucleoside reverse transcriptase inhibitor (NRTI) and NNRTI exposure with introduction of NNRTI-and NRTI- containing triple antiretroviral therapy (ART) earlier in gestation and at higher CD4 cell counts. In a high HIV prevalence setting, overall, 51% of HIV PCR positive infants showed HIV-1 drug resistance, 37% in 2010, 64% in 2011 and 63% in 2012, particularly to the NNRTI drug class. The prevalence of resistance was highest among infants whose maternal antiretroviral therapy (ART) coverage increased across the years, starting earlier in gestation and at higher CD4 cell counts. This is bothering given an increasing lifetime maternal ART coverage for HIV positive pregnant and lactating women. Also of concern is the detection of resistant virus in HIV positive infants whose mothers were not exposed to the antiretroviral drugs, raising questions about circulating resistant virus. As the numbers in this group were too small, trends over the 3 years could not be assessed.