How is shingles (varicella-zoster virus infection) spread?

How Shingles is Spread

Shingles (herpes zoster) spreads through direct contact with fluid from active vesicular lesions and can only cause chickenpox—not shingles—in susceptible individuals who have never had chickenpox or the varicella vaccine. 1

Primary Transmission Mechanism

Direct contact transmission is the predominant route:

• The varicella-zoster virus (VZV) transmits through direct contact with fluid from shingles vesicles 1
• A person with shingles cannot give another person shingles directly—they can only transmit VZV, which causes chickenpox in susceptible individuals 1
• Shingles itself occurs only as a reactivation of latent virus in someone who previously had chickenpox or the vaccine 1

Airborne Transmission (Healthcare Settings)

While less common than direct contact, airborne transmission is documented:

• Airborne transmission of VZV has been demonstrated in hospitals when varicella occurred in susceptible persons who had no direct contact with the index case-patient 2
• This route is primarily documented in healthcare settings, not through casual community contact 1
• Nosocomial transmission has resulted from patients, hospital staff, and visitors infected with varicella or herpes zoster 2

Relative Contagiousness

Shingles is significantly less contagious than chickenpox:

• Herpes zoster is approximately 20% as transmissible as chickenpox 1
• Household transmission risk is approximately 20% of the risk seen with chickenpox 1
• Localized herpes zoster is much less infectious than varicella; disseminated herpes zoster is considered as infectious as varicella 2
• Individuals with shingles pose minimal risk to others if lesions are covered and direct contact is avoided 1

Contagious Period

The timeline of infectivity is critical for isolation decisions:

• Contagiousness begins 1-2 days before the onset of rash 1
• Contagiousness continues until all lesions have dried and crusted, typically 4-7 days after rash onset 1
• For lesions that do not crust (macules and papules), contagiousness ends when no new lesions appear within a 24-hour period 1
• Immunocompromised patients may experience slower healing (7-14 days or longer) and prolonged viral shedding 1

High-Risk Populations to Avoid

Patients with active shingles must avoid contact with:

• Pregnant women 1
• Premature infants and neonates 2, 1
• Immunocompromised persons of all ages 2, 1
• Anyone without history of chickenpox or varicella vaccination 1

These groups are at increased risk for severe disease if exposed and infected. 1

Practical Prevention Measures

To minimize transmission risk:

• Cover all lesions completely 1
• Wash hands frequently with soap and water 1
• Use separate towels and pillows from household members 1
• Avoid contact with high-risk individuals until all lesions are crusted 1

Common Pitfalls to Avoid

• Do not assume that starting antiviral therapy immediately makes the patient non-contagious—viral shedding continues until lesions are fully crusted 1
• Do not allow inadequate covering of lesions, which can lead to transmission even with localized disease 1
• Do not underestimate the contagious period in immunocompromised patients, who may have prolonged viral shedding 1
• Do not overlook airborne precautions in healthcare settings, particularly when caring for immunocompromised patients 2