Nevirapine resistance in human immunodeficiency virus type 1-positive infants determined using dried blood spots stored for up to six years at room temperature.

Dried blood spots that had been stored ambiently for 3 to 6 years lost approximately 1 log(10) of human immunodeficiency virus type 1 (HIV-1) RNA, but the majority could still be genotyped for resistance. Nevirapine resistance was found in 7/16 (43.5%) HIV-1-positive HIVNET 024 infants at 4 to 6 weeks, but no resistance was found at other time points.