baby earCongenital cytomegalovirus (CMV) infection, the most frequently transmitted intrauterine infection, is the leading nongenetic cause of hearing loss, accounting for 21% of cases at birth and 24% at 4 years of age. It is also the leading viral cause of mental retardation. An article in the March 5, 2015 issue of the New England Journal Medicine co-authored by Sandra L. Fowler, M.D., MSc, Director of Pediatric Infectious Diseases at MUSC Children’s Hospital, and other members of the National Institute of Allergy and Infectious Diseases Collaborative Antiviral Study Group (CASG), reported the results of a double-blinded, randomized, placebo-controlled trial of oral valganciclovir in neonates with symptomatic CMV infection (NCT00466817).1 A 2003 trial by the CASG of intravenous (IV) ganciclovir in neonates with CMV infection and central nervous system involvement showed that 6 weeks of ganciclovir therapy resulted in better hearing at 6 months but suggested that those gains were not durable.2 The recently completed CASG trial randomized neonates to either 6 weeks or 6 months of treatment with oral valganciclovir, a prodrug of ganciclovir, and assessed changes at 6, 12, and 24 months in better-ear and overall hearing and performance on a neurodevelopmental test, particularly as it related to linguistic and communication ability. No significant differences in hearing were noted between the two groups at 6 months, but improved hearing was 3 times as likely at 12 months and 2.6 times as likely at 24 months in study patients receiving 6 months vs 6 weeks of therapy. Those receiving 6 months of therapy also scored higher on the Bayley III assessment of neurodevelopment in the language-composite component and the receptive-communication scale, with low average results vs the borderline results seen in neonates receiving only 6 weeks of therapy. Neutropenia (i.e., a reduced number of neutrophils), which can be a concern in neonates taking IV ganciclovir, posed less of an issue with the oral administration of valganciclovir over the course of 6 months. According to Fowler, these results represent “a big step forward in our ability to improve outcomes in infants with congenital CMV and will establish a new standard of care. Our next step will be to determine whether infants who are asymptomatically infected with CMV—but still at risk for developing hearing loss—will benefit from antiviral therapy, as well.”