This document discusses whether valganciclovir is the best preventive treatment for cytomegalovirus (CMV). It begins by introducing CMV as a herpes virus that infects over 80% of adults without symptoms. The document then reviews several studies that tested valganciclovir or ganciclovir treatments in transplant patients and infants. The studies found success rates from 68-96% depending on dosage and duration. The document concludes that valganciclovir is superior to other approved treatments and that combining intravenous then oral medications provides the best prevention and treatment of CMV.