Contagiousness of Herpes Zoster After Antiviral Therapy
People with herpes zoster should remain isolated from others until all rash lesions have crusted over and are dry. [1] Antiviral therapy does not change the infection-control endpoint, which remains crusting of vesicular lesions. [1]
Isolation Duration Endpoint
Isolation should continue until:
- All shingles lesions have crusted over. [1]
- The rash is no longer vesicular (virus transmission from blister fluid and airborne virus particles ends when lesions crust). [1]
Timing After Rash Development
Shingles blisters typically scab over in about 7 to 10 days after rash onset. [2] Isolation duration therefore commonly ends when scabbing has completed, with timing dependent on lesion progression. [2]
Practical Isolation During Antiviral Course
Active herpes zoster lesions are infectious during the vesicular stage. [1] If lesions can be completely covered and are no longer vesicular, transmission risk is reduced substantially. [1]
High-Risk Contact Considerations
Direct contact with the rash vesicles should be avoided until the rash has crusted over. [1] Exposure risk remains relevant for contacts who are pregnant, immunocompromised, or not immune to varicella. [1]
Sources of Guidance Used
CDC infection-control guidance for varicella-zoster virus states that active herpes zoster is contagious when rash lesions are vesicular and is no longer infectious to others once lesions have crusted over. [1] CDC shingles patient and clinical resources support the same crusting-based endpoint. [1], [2]