Valerie Chiang,1 Kelvin Kai Wang To,2 Ivan Fan Ngai Hung,3 Chinmoy Saha,4 Jackie SH Yim,4 Jane Chi Yan Wong,4 Elaine YL Au,1 Tik Suet Chan,4 Andy Ka Chun Kan,4 Yuh Dong Hong,5 Jiaxi Ye,5 Carmen S Ng,5 Carmen TK Ho,4 Chak Sing Lau,4 Tommy TY Lam,5 Esther WY Chan,6 Jianchao Quan,5 Philip Hei Li4

1 Division of Clinical Immunology, Department of Pathology, Queen Mary Hospital, Hong Kong
2 Department of Microbiology, Queen Mary Hospital, The University of Hong Kong, Hong Kong
3 Division of Infectious Diseases, Department of Medicine, Queen Mary Hospital, The University of Hong Kong, Hong Kong
4 Division of Rheumatology and Clinical Immunology, Department of Medicine, Queen Mary Hospital, The University of Hong Kong, Hong Kong
5 School of Public Health, The University of Hong Kong, Hong Kong
6 Centre for Safe Medication Practice and Research, Department of Pharmacology and Pharmacy, The University of Hong Kong, Hong Kong

Abstract

Background: Misdiagnosed vaccine-related “allergies” lead to unnecessary vaccine deferrals and incomplete vaccinations, leaving patients unprotected against COVID-19. To overcome limitations and queues for Allergist assessment, the “VAS-Track” pathway was developed to evaluate patients via a multi-disciplinary triage model including nurses, non-specialists, and Allergists.
Objective: We assessed the effectiveness and safety of VAS-Track and evaluate its real-world impact in terms of vaccination rates and COVID-19 protection.
Methods: Patients referred to VAS-Track between September 2021 and March 2022 were recruited. Subgroup analysis was performed with prospective pre- and post-clinic antibody levels.
Results: Nurse-assisted screening identified 10,412 (76%) referrals as inappropriate. 369 patients were assessed by VAS-Track. Overall, 100% of patients were recommended to complete vaccination and 332 (90%) completed their primary series. No patients reported any significant allergic reactions following subsequent vaccination. Vaccination completion rates between patients seen by non-specialists and additional Allergist review were similar (90% vs. 89%, p = 0.617). Vaccination rates were higher among patients with prior history of immediate-type reactions (odds ratio: 2.43, p = 0.025). Subgroup analysis revealed that only 20% (56/284) of patients had seropositive COVID-19 neutralizing antibody levels (≥ 15 AU/mL) prior to VAS-Track, which increased to 92% after vaccine completion (pre-clinic antibody level 6.0 ± 13.5 AU/mL vs. post-clinic antibody level 778.8 ± 337.4 AU/mL, p < 0.001).
Conclusion: A multi-disciplinary allergy team was able to streamline our COVID-19 VAS services, enabling almost all patients to complete their primary series, significantly boosting antibody levels and real-world COVID-19 protection. We propose similar multidisciplinary models to be further utilized, especially in the settings with limited allergy services.
Key words: Allergy, Antibody, COVID-19, Vaccine, Safety