VAX-SAFE: Vaccination Safety Scoring for Immunosuppressed Patients

1. Introduction

Patients with rheumatic and autoimmune diseases face a dual vulnerability: increased infection risk from both disease-mediated immune dysregulation and iatrogenic immunosuppression, coupled with reduced vaccine immunogenicity and safety concerns—particularly with live attenuated vaccines. The ACR 2022 Guideline for Vaccinations in Patients with Rheumatic and Musculoskeletal Diseases and EULAR 2019 recommendations provide framework guidance, but clinical implementation requires integrating multiple patient-specific variables into actionable decisions.

VAX-SAFE operationalizes these guidelines into a composite weighted score (0-100) that classifies each vaccine-patient pair into five risk categories: Safe (≥80), Conditional (60-79), Caution (40-59), High Risk (20-39), and Contraindicated (<20).

2. Methods

2.1 Immunosuppression Classification

Medications classified into three tiers per ACR/EULAR:

• Low: HCQ, SSZ, LEF, APR, MTX ≤15mg/wk
• Moderate: MTX >15mg, AZA, MMF, TAC, JAKi (tofacitinib, baricitinib, upadacitinib), TNFi, IL-6i, CTLA4-Ig, IL-17i, IL-23i, prednisone ≤10mg, BEL, VOC, ANI
• High: RTX, CYC, prednisone >20mg

2.2 Scoring Algorithm

$$S = S_{base} - P_{live}(I) - P_{activity} - P_{lymph} - P_{IgG} - P_{age} - P_{pregnancy} - P_{splenectomy} - P_{reactions}$$

Where:

• $S_{base}$: Vaccine-specific baseline safety (85-96)
• $P_{live}(I)$: Live vaccine penalty by immunosuppression level (0/15/40/80)
• $P_{activity}$: Disease activity penalty (0/2/5/10)
• $P_{lymph}$: Lymphopenia penalty (0/10/20 for >1000/500-1000/<500 cells/μL)
• $P_{IgG}$: Hypogammaglobulinemia (0/8/15 for >700/400-700/<400 mg/dL)

2.3 Monte Carlo Sensitivity Analysis

5,000 simulations perturbing:

• Lymphocyte count: Gaussian noise, CV=15%
• IgG: Gaussian noise, CV=10%
• Disease activity: 10% probability of ±1 level shift

Outputs: mean, median, 5th-95th percentile CI, %safe, %contraindicated.

2.4 Timing Logic

Drug-specific hold recommendations per ACR 2022:

• Methotrexate: hold 1-2 weeks post non-live vaccination
• Rituximab: vaccinate ≥6mo post-dose, ≥4wk pre-next, target CD19 >10/μL
• JAK inhibitors: hold 1 week post vaccination
• Abatacept IV: vaccinate 1 week before next dose
• Live vaccines: hold all IS ≥4wk before, ≥2wk after

3. Results

Scenario 1: RA, MTX + adalimumab

• Inactivated influenza: 88 (Safe)
• RZV Shingrix: 85 (Safe)
• ZVL Zostavax: 43 (Caution — live vaccine)

Scenario 2: SLE, rituximab + prednisone >20mg, lymphopenic

• COVID mRNA: 57 (Caution — efficacy concern)
• MMR: 0 (Contraindicated)
• Monte Carlo COVID: mean 56.8, 95% CI [47, 62]

Scenario 3: Pregnant SLE on HCQ

• Influenza inactivated: 92 (Safe)
• MMR: 27 (Contraindicated — pregnancy + live)

4. Discussion

VAX-SAFE bridges guideline recommendations and clinical workflow by producing a single actionable score with transparent breakdown. The Monte Carlo component addresses measurement uncertainty in laboratory values and the inherent stochasticity of disease activity assessment.

Key design decisions: (1) absolute contraindication for live vaccines in high immunosuppression regardless of other factors, (2) rituximab-specific timing as mandatory warning due to B-cell depletion kinetics, (3) pregnancy as independent contraindication for live vaccines per ACOG/CDC.

References

1. Bass AR, et al. 2022 American College of Rheumatology Guideline for Vaccinations in Patients with Rheumatic and Musculoskeletal Diseases. Arthritis Care Res. 2023;75(3):449-464. doi:10.1002/acr.25045
2. Furer V, et al. 2019 update of EULAR recommendations for vaccination in adult patients with autoimmune inflammatory rheumatic diseases. Ann Rheum Dis. 2020;79(1):39-52. doi:10.1136/annrheumdis-2019-215882
3. Rubin LG, et al. 2013 IDSA clinical practice guideline for vaccination of the immunocompromised host. Clin Infect Dis. 2014;58(3):e44-e100. doi:10.1093/cid/cit684
4. Curtis JR, et al. American College of Rheumatology Guidance for COVID-19 Vaccination in Patients with Rheumatic and Musculoskeletal Diseases. Arthritis Rheumatol. 2021;73(8):e30-e45.
5. Friedman MA, et al. Impact of disease-modifying antirheumatic drugs on vaccine immunogenicity in patients with inflammatory rheumatic and musculoskeletal diseases. Ann Rheum Dis. 2021;80(10):1255-1265.