Is there a risk of shingles transmission to immunocompetent (having a normally functioning immune system) individuals from patients with a new shingles rash?

Risk of Shingles Transmission to Immunocompetent Individuals

Yes, there is a real but relatively low risk of transmission from patients with shingles to immunocompetent people, though localized shingles is much less infectious than chickenpox or disseminated shingles. 1

Understanding the Transmission Risk

Localized vs. Disseminated Shingles

• Localized shingles (herpes zoster) is significantly less infectious than chickenpox (varicella), with transmission occurring primarily through direct contact with uncovered lesions rather than airborne spread 1
• Disseminated shingles is considered as infectious as chickenpox and can spread through airborne transmission 1
• Immunocompetent patients with localized shingles pose a lower transmission risk compared to immunocompromised patients with either localized or disseminated disease 1

Documented Transmission Events

Both localized and disseminated shingles in immunocompetent and immunocompromised patients have been identified as sources of nosocomial (healthcare-acquired) varicella transmission 1. This means the virus from shingles lesions can cause chickenpox in susceptible contacts who have never had varicella or vaccination.

• In healthcare settings, airborne transmission from shingles patients has resulted in chickenpox in individuals who had no direct contact with the index patient 1
• Individuals suffering from shingles may be contagious to susceptible children due to the enormous amount of virus particles in vesicle fluid 2

Who Is at Risk?

Susceptible Immunocompetent Contacts

The primary concern is transmission to immunocompetent individuals without evidence of immunity (those who have never had chickenpox or varicella vaccination) 1:

• Approximately 98% of persons aged 20-49 years have varicella-zoster virus (VZV)-specific antibodies, meaning most adults are already immune 1
• Susceptible contacts exposed to shingles patients can develop chickenpox, not shingles 2, 3
• The household setting represents the highest-risk exposure scenario, with 65-100% attack rates in susceptible household contacts exposed to varicella 4, 5

Exposure Definition

Close contact is defined as indoor contact in the same room or face-to-face contact, with experts suggesting durations ranging from 5 minutes to 1 hour, but not including transitory contact 1

Clinical Management Approach

For the Shingles Patient

Immunocompetent persons with localized shingles require standard precautions and complete covering of the lesions 1. This is in contrast to:

• Patients with varicella or disseminated shingles who require airborne precautions (negative air-flow rooms) and contact precautions until lesions are dry and crusted 1
• Immunocompromised patients with localized shingles who should be isolated until disseminated infection is ruled out 1

For Exposed Immunocompetent Contacts

Post-exposure varicella vaccination is the primary intervention for susceptible immunocompetent contacts 4, 3:

• Varicella vaccine administered within 3 days of exposure is >90% effective in preventing disease 4
• Vaccine given within 5 days is 70% effective in preventing disease and 100% effective in modifying severe disease 4
• The vaccine is licensed for healthy persons aged >12 months 4

Varicella-zoster immune globulin (VariZIG) is NOT indicated for healthy immunocompetent contacts—it is reserved for immunocompromised patients, pregnant women, neonates with specific maternal exposure timing, and premature infants 4, 5

Important Caveats

Infectivity Factors

• The risk of transmission correlates with the number and extent of skin lesions—more extensive rashes pose higher transmission risk 1
• Patients with shingles are infectious from the time vesicles appear until all lesions are crusted 1
• The virus is transmitted through direct contact with lesion fluid or, less commonly in localized disease, through airborne particles 1

Healthcare Setting Considerations

Only healthcare personnel with evidence of immunity to varicella should care for patients with confirmed or suspected shingles 1. This recommendation exists because:

• Nosocomial VZV transmission is well-recognized and can be disruptive, time-consuming, and costly even when it doesn't result in actual transmission 1
• A single provider with unrecognized varicella can expose >30 patients and >30 employees 1

Breakthrough Considerations

Even immunocompetent individuals who receive post-exposure vaccination may develop mild breakthrough varicella, typically presenting with <50 lesions, shorter duration, and lower fever than unvaccinated cases 4