Risk of Side Effects with Concurrent Shingrix and High-Dose Flu Vaccine
The risk of severe side effects when receiving the first dose of Shingrix and high-dose influenza vaccine simultaneously is not increased compared to receiving them separately, with approximately 11-13% of patients experiencing at least one severe local or systemic reaction. 1
Key Safety Data
The most recent 2024 ACIP guidelines specifically address this combination based on a randomized controlled trial (CISA RCT) in adults ≥65 years. This study directly compared:
- Shingrix dose 1 + high-dose influenza vaccine (HD-IIV) versus
- Shingrix dose 1 + adjuvanted influenza vaccine (aIIV)
The proportion of participants with at least one severe local or systemic reaction was NOT higher with the high-dose flu vaccine combination 1. The research trial found 12.5% experienced severe reactions with HD-IIV versus 11.5% with aIIV—essentially equivalent 2.
Expected Side Effects
Common Non-Severe Reactions (Most Frequent):
- Injection site reactions: 65% of cases 3
- Myalgia (muscle pain): 38-64% 4
- Fever: 7-16% 1, 5
- Chills/shivering: 7-21% 1, 5
- Fatigue: Common but percentage not specified
Important Context:
Most reactogenicity symptoms resolve within 4 days 1. The FDA label notes that decreased mobility of the injected arm may persist for 1 or more weeks in some cases 5.
Serious Adverse Events
The safety profile shows:
- Serious adverse events: 6.9% in post-marketing surveillance, with no elevated risk from co-administration 3
- Guillain-Barré syndrome (GBS): Rare association with Shingrix exists (estimated 6 excess cases per million first doses in adults ≥65 years), but no evidence that concurrent flu vaccination increases this risk 5
- No new safety signals detected when vaccines given together 3
Clinical Recommendations
Administration Technique:
Give the vaccines in different limbs if possible, as both high-dose flu vaccine and Shingrix are associated with local injection site reactions 1.
Key Caveat:
While you could consider using a non-adjuvanted flu vaccine to potentially reduce reactogenicity when giving multiple adjuvanted vaccines simultaneously, influenza vaccination should not be delayed if a specific vaccine is not available 1. The high-dose flu vaccine is often the preferred formulation for adults ≥65 years due to superior efficacy.
Bottom Line for Patient Counseling
The combination is safe and supported by current guidelines. Patients should expect:
- Higher likelihood of arm soreness, muscle aches, and possibly fever/chills compared to either vaccine alone
- Symptoms typically resolve within 4 days
- The benefits of protection against both shingles and influenza outweigh the temporary discomfort
- No evidence of increased serious complications from concurrent administration