Can herpes zoster be transmitted to others, and what precautions are needed to prevent spread to susceptible contacts?

Shingles Transmission and Contagiousness

Yes, herpes zoster (shingles) is contagious and can transmit varicella-zoster virus (VZV) to susceptible individuals through direct contact with active lesions, causing chickenpox (not shingles) in those who have never had chickenpox or vaccination. 1

Understanding the Transmission Mechanism

• Shingles cannot directly cause shingles in another person—it can only transmit VZV to susceptible individuals, resulting in primary chickenpox infection. 1
• Transmission occurs through direct contact with fluid from active vesicles or, rarely in healthcare settings, through airborne exposure to viral particles from uncrusted lesions. 1
• Shingles is approximately 20% as contagious as chickenpox, making it significantly less transmissible than primary varicella infection. 1
• Unlike chickenpox (which spreads easily through airborne routes), shingles poses minimal risk if lesions are covered and direct contact is avoided. 1

Contagious Period: When Isolation is Required

The contagious period begins 1-2 days before rash onset and continues until all lesions have dried and crusted, typically 4-7 days after rash appears. 1

• For lesions that do not crust (macules and papules), contagiousness ends when no new lesions appear within a 24-hour period. 1
• Starting antiviral therapy does NOT immediately render the patient non-contagious—viral shedding continues until lesions are fully crusted. 1
• Immunocompromised patients experience slower healing (7-14 days or longer) and may have prolonged viral shedding beyond the typical timeframe. 1

High-Risk Populations Requiring Strict Avoidance

Patients with active shingles must avoid contact with:

• Pregnant women (particularly those without prior chickenpox or vaccination) 1
• Premature infants and neonates 1
• Immunocompromised individuals (cancer patients, transplant recipients, HIV-positive individuals, those on immunosuppressive therapy) 1
• Anyone without history of chickenpox or varicella vaccination 1

Special Consideration for Newborns

• Newborns whose mothers develop varicella from 5 days before to 2 days after delivery face 17-30% risk of severe infection with historical mortality of 31%. 1
• Maternal herpes zoster during pregnancy does not cause congenital varicella syndrome (unlike maternal chickenpox). 1

Infection Control Precautions by Clinical Scenario

For Immunocompetent Patients with Localized Herpes Zoster

• Standard and contact precautions are sufficient—airborne precautions are NOT required. 1
• Cover all lesions completely with clothing or dressings. 1
• Maintain at least 6 feet physical separation from other patients in healthcare settings. 1
• Patient should wear a surgical mask to prevent droplet transmission. 1
• Continue precautions until all lesions are dried and crusted (typically 4-7 days after rash onset). 1

For Disseminated Herpes Zoster or Immunocompromised Patients

Airborne and contact precautions are mandatory, regardless of immune status. 1

• Requires negative air-flow room (negative pressure isolation). 1
• Continue precautions until all lesions are dry and crusted. 1
• Immunocompromised patients with ANY herpes zoster require airborne and contact precautions until disseminated infection is ruled out. 1
• These patients experience prolonged viral shedding and slower healing. 1

Healthcare Worker Restrictions

Healthcare workers with localized herpes zoster who are immunocompetent must:

• Cover all lesions completely. 1
• Be restricted from caring for high-risk patients (immunocompromised, pregnant women, neonates, patients in protective environments) until all lesions have dried and crusted. 1

Healthcare workers with disseminated zoster or localized zoster who are immunocompromised must:

• Be excluded from duty entirely until all lesions have dried and crusted. 1

Return to Work Criteria

• For non-crusting lesions, complete work clearance is permitted when no new lesions appear within 24 hours. 1
• Standard precautions with complete lesion coverage are mandatory even after return to work in high-risk settings. 1

Practical Prevention Measures for Patients

To minimize transmission risk, patients should:

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

Common Pitfalls to Avoid

• Assuming antiviral therapy immediately makes the patient non-contagious—viral shedding continues until lesions are fully crusted. 1
• Allowing healthcare workers with herpes zoster to care for high-risk patients before lesions are fully crusted. 1
• Inadequate covering of lesions, which can lead to transmission even with localized disease. 1
• Failing to recognize that immunocompromised patients may have prolonged periods of viral shedding and contagiousness. 1
• Underestimating airborne transmission risk in healthcare settings, particularly with disseminated disease. 1

Post-Exposure Prophylaxis for Susceptible Contacts

If a susceptible individual (no history of chickenpox or vaccination) is exposed:

• Varicella zoster immunoglobulin (VZIG) or intravenous immunoglobulin within 96 hours of exposure is recommended. 2
• If immunoglobulin is unavailable or more than 96 hours have passed, a 7-day course of oral acyclovir beginning 7-10 days after exposure is recommended. 2
• VZIG provides maximum benefit when administered as soon as possible after exposure. 2

Important Clarification About Re-Exposure

Individuals who have already had shingles are immune to VZV and cannot acquire a new infection from external exposure. 3

• Exposure to someone with chickenpox or shingles does NOT trigger shingles recurrence. 3
• Only VZV-susceptible individuals (no history of chickenpox/shingles or seronegative) need to avoid exposure. 3
• Neither VZIG nor acyclovir prophylaxis is needed for individuals with prior shingles history. 3