Clearance for Shingrix and Flu Vaccines After COVID-19 Vaccine-Associated Seizure
Yes, this patient can safely receive both Shingrix and influenza vaccines, as these are mechanistically distinct from COVID-19 vaccines and do not share the same adverse event profile.
Key Clinical Reasoning
The critical distinction here is that a seizure following COVID-19 vaccination does not predict or contraindicate other vaccines. The evidence shows:
COVID-19 vaccines have unique safety signals that are specific to their platform (mRNA or adenovector), including rare neurological events like Guillain-Barré syndrome and seizures, but these are not generalizable to other vaccine types 1.
Shingrix and influenza vaccines have well-established safety profiles that are distinct from COVID-19 vaccines, with decades of surveillance data showing no significant seizure risk 1.
The mechanism of a COVID-19 vaccine-associated seizure is likely related to either the novel mRNA/lipid nanoparticle platform or adenovector components, or represents an immunization stress-related response (ISRR) manifesting as psychogenic non-epileptic seizures (PNES), rather than a generalized vaccine hypersensitivity 1.
Evidence Supporting Safe Administration
Shingrix Safety Profile
Shingrix is a recombinant subunit vaccine containing only a viral glycoprotein fragment with AS01B adjuvant, fundamentally different from COVID-19 vaccine platforms 2.
No seizure signals have been identified in extensive post-licensure surveillance of Shingrix, with the most common adverse events being injection-site reactions (9.5% grade 3) and systemic symptoms (11.4%), which are generally mild to moderate 2.
Co-administration studies with influenza vaccines showed no safety concerns when Shingrix was given simultaneously with unadjuvanted IIV4 1.
Influenza Vaccine Safety Profile
Febrile seizures in children aged 6-23 months have been documented with co-administration of IIV and PCV13 or DTaP, but these are brief with good prognosis and do not represent a contraindication 1.
In adults, no seizure risk has been identified with influenza vaccination across multiple seasons of surveillance through VAERS and VSD 1.
Influenza vaccines can be safely co-administered with other inactivated vaccines, including COVID-19 vaccines, at separate anatomical sites 1, 3.
Practical Implementation Algorithm
Step 1: Verify the seizure was truly vaccine-related
- Confirm temporal association (typically within 2-3 days of COVID-19 vaccination) 1.
- Rule out other causes: metabolic derangements, structural brain lesions, infection, medication changes 4.
- Document whether this was a new-onset seizure or exacerbation of pre-existing epilepsy 5, 6.
Step 2: Proceed with Shingrix and influenza vaccination
- Administer both vaccines at separate anatomical sites (different limbs preferred) 1, 3.
- No waiting period required between these vaccines and the prior COVID-19 vaccination event 1, 3.
- Use standard inactivated influenza vaccine (IIV4 or RIV4), not live attenuated influenza vaccine (LAIV) 1.
Step 3: Monitoring considerations
- Observe for 15-30 minutes post-vaccination as standard practice 1.
- Counsel on expected side effects: injection-site reactions, myalgia, fatigue (most resolve within 4 days for Shingrix) 2.
- No special neurological monitoring is required beyond standard post-vaccination observation 1.
Important Caveats and Pitfalls
Do NOT withhold these vaccines based on COVID-19 vaccine history
Cross-reactivity between vaccine platforms is not established - a reaction to one vaccine type does not predict reactions to mechanistically different vaccines 1, 7, 8.
The benefits substantially outweigh theoretical risks: Herpes zoster causes significant morbidity (post-herpetic neuralgia in up to 30% of cases), and influenza causes substantial mortality in adults, particularly those ≥65 years 2, 1.
Avoid confusing this scenario with true contraindications
True contraindications to Shingrix: severe allergic reaction to a previous dose or any component 2.
True contraindications to influenza vaccine: severe allergic reaction to a previous dose, egg allergy (for egg-based vaccines), or Guillain-Barré syndrome within 6 weeks of a previous influenza vaccination 1.
A seizure after COVID-19 vaccination is NOT a contraindication to other vaccines 1.
Consider deferring only if acute illness present
Moderate to severe acute illness (with or without fever) is a precaution for any vaccination, but minor illnesses are not contraindications 1, 3.
If the patient had recent COVID-19 infection, defer until acute symptoms resolve, but this is unrelated to the prior seizure 1.
Special Considerations for Future COVID-19 Vaccination
While not the primary question, it's worth noting:
Future COVID-19 vaccination should be carefully considered given the prior seizure, though the benefits may still outweigh risks depending on individual circumstances 1.
If future COVID-19 vaccination is pursued, consider a different vaccine platform (e.g., if mRNA caused the seizure, consider protein-based Novavax) and ensure close monitoring 1.
Document the adverse event in VAERS to contribute to ongoing safety surveillance 9.