Valacyclovir, acyclovir, and famciclovir are antiviral medications that are active against herpesviruses, including varicella zoster virus. The risk of shingles risk is reduced during antiviral treatment. Since Shingrix is not a live virus vaccine, Shingrix may be administered while patients are taking antiviral medications if indicated.
A patient who is taking a prophylactic antiviral for a fixed period of time while their immune system recovers from HCT, should ideally initiate vaccination with Shingrix about 2 months prior to discontinuation of antiviral therapy.
Regardless of the duration of antiviral therapy after HCT, CDC recommends that autologous HCT recipients wait at least 3 months after transplant before initiating Shingrix vaccination. Allogenic HCT recipients should wait at least 6 months after transplantation. For additional details on timing after HCT, see www.cdc.gov/shingles/vaccination/immunocompromised-adults.html#clinical-guidance.