Can a Patient Immunized Against Varicella Zoster Still Get Shingles?
Yes, patients immunized against varicella zoster can still develop shingles, as the vaccine does not completely eliminate the risk of reactivation. 1
Mechanism of Shingles Development
The varicella-zoster virus (VZV) that causes chickenpox can establish latency in nerve ganglia after either:
- Natural chickenpox infection
- Vaccination with the varicella vaccine
This latent virus can later reactivate as shingles (herpes zoster) under certain conditions:
- The varicella vaccine contains a weakened form of the virus that can establish latency in nerve ganglia, similar to wild-type virus 1
- After primary infection (either natural or vaccine-strain), the virus becomes dormant in sensory nerve ganglia 2
- Reactivation occurs when cellular immunity declines, leading to virus replication and the characteristic painful, vesicular rash of shingles 3
Risk of Shingles After Vaccination
Vaccine-Strain Shingles
- It is possible, though rare, to develop shingles from the vaccine-strain virus 1
- Studies suggest that the risk of developing vaccine-strain shingles is lower than the risk of developing shingles after natural chickenpox infection 4
- In a study of leukemic children, the rate of herpes zoster after a mean 4.1 years of follow-up was only 2% in vaccine recipients compared to 15% in controls with a history of natural varicella 4
Long-term Risk
- A long-term follow-up study of healthy adults who received the varicella vaccine 10-26 years prior found only 2 cases of herpes zoster among approximately 2,000 person-years of follow-up (rate of 1.00 case/1000 person-years) 5
- This rate is similar to the background rate in the unvaccinated population during the pre-vaccine era, suggesting vaccination does not increase risk 5
Risk Factors for Shingles
Several factors increase the risk of shingles reactivation, regardless of whether the initial infection was from natural disease or vaccination:
- Advanced age 1
- Immunocompromised status 1
- Acquisition of chickenpox during the first year of life 1
- Decline in cellular immune response 3
- Use of steroids 3
- Malignancies 3
- Hard physical work 3
Special Considerations
Immunocompromised Individuals
- Severely immunocompromised patients should avoid live varicella vaccines 1
- Immunocompromised individuals are at higher risk for more severe shingles with potential for cutaneous dissemination and visceral involvement 3
- HIV-infected patients may experience shingles with involvement of multiple dermatomes and more frequent recurrences 3
Vaccination Recommendations
- The CDC recommends shingles vaccination for adults 50 years and older, regardless of whether they recall having had chickenpox 1
- For individuals known to be VZV-seronegative, some guidelines suggest immunization with 2 doses of varicella vaccine with an interval of 4 weeks 1
- If you have active shingles, you should wait until the acute phase has resolved before getting vaccinated 1
Conclusion
While vaccination against varicella zoster significantly reduces the risk of developing shingles compared to natural infection, it does not provide complete protection. The vaccine-strain virus can establish latency and potentially reactivate later in life, although this occurs less frequently than with wild-type virus. Therefore, even immunized individuals should be aware of the possibility of developing shingles and should consider shingles vaccination when appropriate based on age and risk factors.