Is shingles (herpes zoster) contagious?

Shingles (Herpes Zoster) Contagiousness

Yes, shingles (herpes zoster) is contagious, but only to people who have never had chickenpox or the varicella vaccine. 1, 2 The virus that causes shingles (varicella-zoster virus) can be transmitted and cause primary varicella (chickenpox) in susceptible individuals.

Transmission Mechanism

• Shingles is caused by reactivation of the varicella-zoster virus (VZV) that remains dormant in sensory nerve ganglia after a primary chickenpox infection 2
• VZV is transmitted through direct contact with the vesicular fluid from skin lesions or through inhalation of aerosols from these lesions 1
• The virus can also be transmitted through infected respiratory tract secretions that may become aerosolized 1
• The virus enters a susceptible host through the upper respiratory tract or the conjunctivae 1

Period of Contagiousness

• An infected person becomes contagious approximately 1-2 days before the onset of the rash 1, 2
• Contagiousness continues until all lesions have dried and crusted, typically 4-7 days after the onset of rash 1, 2
• For lesions that do not crust (macules and papules), contagiousness ends when no new lesions appear within a 24-hour period 2
• Persons with progressive shingles (development of new lesions for >7 days) might be contagious for longer periods due to depressed immune response allowing continued viral replication 1, 2

Who Is at Risk of Catching the Virus

• Only individuals who have never had chickenpox or received the varicella vaccine are at risk of developing chickenpox after exposure to someone with shingles 1
• People who have had chickenpox or the varicella vaccine are generally immune and will not develop chickenpox from exposure to someone with shingles 1
• High-risk individuals include:
  • Immunocompromised persons 2
  • Pregnant women who have never had chickenpox 1
  • Newborns whose mothers have never had chickenpox 1

Precautions to Prevent Transmission

• Cover all lesions completely to prevent direct contact 2
• Avoid contact with susceptible individuals until all lesions have dried and crusted 1
• Healthcare workers with shingles should be restricted from caring for high-risk patients until lesions have dried and crusted 2
• Household contacts (especially children) of susceptible individuals should be vaccinated against VZV if they have no history of chickenpox and are seronegative for HIV 1

Special Considerations

• Breakthrough varicella (chickenpox that develops in vaccinated individuals) is also contagious, though typically less so than natural varicella 1
• Immunocompromised patients may experience slower healing of lesions (7-14 days or longer) and may have prolonged periods of viral shedding 2
• Starting antiviral therapy does not immediately render the patient non-contagious; viral shedding continues until lesions are fully crusted 2

Common Misconceptions

• Misconception: Shingles itself is not contagious
  • Reality: While you cannot "catch" shingles from someone with shingles, the virus can be transmitted and cause chickenpox in susceptible individuals 1
• Misconception: Starting antiviral medication immediately makes the patient non-contagious
  • Reality: Even with antiviral therapy, patients remain contagious until all lesions have crusted 2
• Misconception: Covering lesions with clothing is sufficient to prevent transmission
  • Reality: Complete covering of all lesions is necessary, and even then, avoiding contact with susceptible individuals is recommended until lesions have crusted 2