‘We will continue to learn from this research about risk elements for HIV transmission, which will bear fruit for both the HIV avoidance and the vaccine fields for years to come.’.. Acyclovir does not reduce risk of HIV transmission for folks infected with both HIV and HSV-2 A five-calendar year international multi-center clinical trial has found that acyclovir, a medication widely used as a safe and effective treatment taken twice daily to suppress herpes simplex virus-2 , which may be the most common reason behind genital herpes, does not reduce the threat of HIV transmitting when taken by people infected with both HIV and HSV-2.Mayo Clinic starts the series at age 9 routinely. ‘The vaccine works better the younger the child is definitely, and it doesn't work after the child is developed and is subjected to the virus, so our message ought to be: 'Give this vaccine now to your son or daughter while your son or daughter is responsive and youthful to it,'’ says Dr. Jacobson, medical director of the Employee and Community Wellness Immunization System at Mayo Clinic. Study co-authors include Paul Darden, M.D., David Thompson, Ph.D., Jessica Hale, and Monique Naifeh, M.D., M.P.H., University of Oklahoma; and James Roberts, M.D., M.P.H., and Charlene Pope, Medical University of SC.