Real-world challenges in eligibility for MMR vaccination two years after autologous and allogeneic HSCT

Area of Science:

• Immunology
• Transplantation Medicine
• Infectious Disease Epidemiology

Background:

• Measles outbreaks pose risks to immunocompromised individuals, particularly post-hematopoietic stem cell transplant (HSCT).
• Current Canadian guidelines recommend measles, mumps, and rubella (MMR) vaccination two years after HSCT.
• Eligibility for MMR vaccination post-HSCT has not been fully assessed considering medication contraindications.

Purpose of the Study:

• To evaluate MMR vaccine immunity and eligibility in autologous (auto-HSCT) and allogeneic (allo-HSCT) recipients.
• To determine the proportion of HSCT recipients on medications that contraindicate MMR vaccination two years post-transplant.

Main Methods:

• Retrospective chart review of 72 auto-HSCT and 68 allo-HSCT recipients.
• Assessment of MMR seroreactivity.
• Identification of patients on contraindicated medications at two years post-HSCT.

Main Results:

• Lower MMR immunity observed in auto-HSCT recipients (49.1% measles, 28.8% mumps, 52.3% rubella) compared to allo-HSCT recipients (75.6% measles, 57.8% mumps, 64.4% rubella).
• Significant differences in immunity to all three MMR components between auto-HSCT and allo-HSCT groups (p=0.0002).
• Nearly 80% of auto-HSCT patients and 45% of allo-HSCT patients were on contraindicated medications two years post-transplant.

Conclusions:

• Autologous HSCT recipients exhibit lower MMR immunity and a higher rate of medication contraindications for MMR vaccination.
• Current guidelines for MMR vaccination post-HSCT may not be suitable for all patients, especially auto-HSCT recipients.
• Further strategies are needed to ensure measles protection in immunocompromised patients post-HSCT who cannot receive live vaccines.