Is a single dose of hepatitis B vaccine sufficient to induce protective immunity in a patient with chronic plaque psoriasis receiving risankizumab?

No, a Single Dose is NOT Sufficient

A single dose of hepatitis B vaccine will NOT induce protective immunity in a patient with chronic plaque psoriasis receiving risankizumab—a complete 3-dose series is required, with post-vaccination serologic testing to confirm adequate antibody response. 1

Vaccination Strategy for Immunocompromised Patients

Complete Series Required

For patients on immunosuppressive biologics like risankizumab (an IL-23 inhibitor):

• Standard approach: Administer the full 3-dose hepatitis B vaccine series 2
• Enhanced dosing may be needed: Consider high-dose formulations (40 µg vs standard 20 µg) to improve response rates in immunocompromised patients 2
• Post-vaccination testing is mandatory: Check anti-HBs levels 1-2 months after completing the series 2

Why One Dose Fails

The evidence is clear that immunocompromised patients have:

• Reduced seroconversion rates: Only 60-70% of patients on immunosuppressive therapy achieve protective antibody levels even with a complete series, compared to >90% in immunocompetent individuals 2
• Dose-dependent response: The immune response builds cumulatively across the 3-dose series—a single dose provides insufficient antigenic stimulation 2
• Rapid seroreversion: Even patients who initially respond may lose protective antibodies over time, requiring booster doses 2

Specific Considerations for Risankizumab

Timing Matters

While the FDA label for risankizumab 3 does not specifically address vaccination timing, general principles for biologics apply:

• Ideally vaccinate before starting therapy when immune function is intact 1
• If already on risankizumab: Continue the biologic during vaccination—IL-23 inhibitors like risankizumab have a more favorable safety profile than older agents and do not require treatment interruption 4, 5
• Do NOT hold risankizumab for hepatitis B vaccination (unlike rituximab or high-dose methotrexate which require temporary discontinuation) 1

Expected Response Rates

For patients on IL-23 inhibitors:

• Better than older immunosuppressants: Biologics targeting IL-17/IL-23 pathways preserve humoral immune responses better than conventional agents like cyclosporine or methotrexate 4
• Still suboptimal: Response rates remain lower than immunocompetent individuals, necessitating the complete series and confirmatory testing 2

Practical Algorithm

1. Administer complete 3-dose series (0,1, and 6 months)
2. Continue risankizumab throughout vaccination—do not interrupt therapy
3. Test anti-HBs levels 1-2 months after dose #3
4. If anti-HBs <10 mIU/mL (non-responder):
   • Repeat entire 3-dose series, OR
   • Give single booster dose and retest (though full series repetition is more effective) 2
5. Consider high-dose vaccine (40 µg) if standard series fails 2

Critical Pitfalls to Avoid

• Do not assume one dose is sufficient based on testing after a single injection—this will miss the majority of patients who would have responded to the complete series
• Do not delay vaccination waiting for "optimal" timing—vaccinate now and continue risankizumab
• Do not skip post-vaccination testing—up to 30-40% of immunocompromised patients fail to respond even to complete series 2
• Age matters: Patients over 55 years have significantly reduced response rates (50% vs 96.8% in those under 40), requiring more aggressive monitoring 6

HBV Reactivation Risk Context

Given that risankizumab carries risk of HBV reactivation in patients with prior exposure 7, 8, achieving protective immunity through complete vaccination is particularly important. The reactivation rate without prophylaxis can reach 26.6%, but drops to 0% with appropriate antiviral coverage 8. Complete vaccination provides the foundation for long-term protection.

Bottom line: One dose is inadequate. Complete the full 3-dose series, continue risankizumab during vaccination, and verify response with post-vaccination serology.