<qa>  What is the name of the urine collected for children that are toilet trained?For children that are toilet trained, urine will be collected for 12 hours at the start of the study. This urine will be used to evaluate kidney function, and the pharmacology of valacyclovir. If there are unacceptable side effects or if there is evidence that the disease is spreading, despite being on Valacyclovir for more than 48 hours, then you will be taken off the study and started on acyclovir by vein. 