Does influenza (flu) vaccination increase the risk of herpes zoster (shingles)?

Influenza Vaccination and Risk of Shingles

Influenza vaccination does not increase the risk of shingles (herpes zoster), with only a slight, temporary increase in risk observed in the first 15 days after vaccination according to the most recent evidence.

Evidence on Influenza Vaccination and Shingles Risk

The relationship between influenza vaccination and herpes zoster has been investigated in several studies:

• The most recent evidence from 2023 shows only a slight increase in herpes zoster risk during the first 15 days after influenza vaccination (IRR = 1.11; 95% CI, 1.02-1.20), but this effect becomes insignificant when looking at a 30-day period (IRR = 1.04; 95% CI, 0.98-1.10) 1

• This temporary, minimal increase is primarily observed in:

  • Adults aged 50-64 years
  • Males
  • Healthier individuals without history of cancer or autoimmune diseases

• In specific populations such as renal transplant recipients (who are at higher risk for shingles due to immunosuppression), no significant association between influenza vaccination and increased herpes zoster risk was found 2

Comparison with Other Vaccine-Associated Risks

The Advisory Committee on Immunization Practices (ACIP) has extensively studied vaccine-associated risks, particularly focusing on Guillain-Barré Syndrome (GBS):

• The estimated risk for GBS after influenza vaccination is approximately 1 additional case per 1 million persons vaccinated 3

• This risk is substantially lower than the risk of severe influenza complications that could be prevented by vaccination 3

• The potential benefits of influenza vaccination in preventing serious illness, hospitalization, and death substantially outweigh the minimal risks of vaccine-associated adverse events 3

Clinical Implications and Recommendations

When considering influenza vaccination in relation to herpes zoster risk:

1. Proceed with recommended influenza vaccination for all eligible patients, as the benefits significantly outweigh any potential minimal, temporary increase in shingles risk

2. Monitor patients with known risk factors for herpes zoster during the first 15 days post-vaccination, particularly:

   • Adults aged 50-64
   • Males
   • Otherwise healthy individuals

3. Educate patients that any potential increased risk is:

   • Very small
   • Limited to a short timeframe (first 15 days)
   • Far outweighed by the benefits of protection against influenza

Practical Considerations

• Patients concerned about shingles should be informed that getting the shingles vaccine (Shingrix) is the most effective way to prevent herpes zoster, rather than avoiding influenza vaccination 4

• For patients with a history of herpes zoster, it's worth noting that this history may be associated with a weaker immune response to the influenza A H1N1 and H3N2 antigens 5, making influenza vaccination even more important in this population

• The social determinants affecting influenza and shingles vaccination uptake differ, with more pronounced racial disparities observed for shingles vaccination compared to influenza vaccination 4

In conclusion, while there may be a slight, temporary increase in herpes zoster risk in the first 15 days following influenza vaccination, this risk is minimal and should not deter vaccination, as the benefits of influenza prevention substantially outweigh this small, short-term risk.