Infectivity of shingles

Classic skin findings are grouped vesicles on a red base in a unilateral, dermatomal distribution. Herpes zoster (HZ) is contagious after the rash appears and until the lesions crust.

• the lesions of herpes zoster (HZ) progress through stages, beginning as red macules and papules that, in the course of 7 to 10 days, evolve into vesicles and form pustules and crusts. Complete healing may take more than 4 weeks (1)
• Herpes zoster lesions contain high concentrations of varicella zoster virus (VZV), which can be spread by contact and by the airborne route and which can cause primary varicella in exposed, susceptible persons. Less contagious than primary varicella, HZ is only contagious after the rash appears and until the lesions crust. Risk of transmission is reduced further if lesions are covered
  • infectious period for localised and disseminated shingles is considered as the time from onset of rash until all of the lesions have crusted over (2)

Notes:

• shingles is not as infectious as chicken pox; but people who have not had chicken pox may get chicken pox as a result of contact with a person with shingles. A person cannot get shingles from a person who has shingles

Reference:

• 1) Homler H.Herpes zoster: query and concern. Mayo Clin Proc. 2009 Jul;84(7):663; author reply 663-4.
• 2) UK Health Security Agency. Guidelines on post exposure prophylaxis (PEP) for varicella and shingles (April 2022)