May 3, 2006—One-fifth of positive women in a small South Africa study by the U.S. National Institutes of Health developed continued resistance to nevirapine after taking it as single-dose monotherapy during pregnancy to prevent mother-to-child transmission. This contradicts previous findings that any nevirapine resistance that mothers developed disappeared within a year. Nevirapine monotherapy is not recommended in the U.S., where the brand name is Viramune.