2361. Prevalence of Zoster Infection Post mRNA COVID-19 Vaccination Compared to Influenza Vaccination

BACKGROUND: Introduction: Varicella-zoster virus (VZV) reactivation was not listed as a side effect of any vaccine until introduction of COVID-19 vaccines. Since COVID-19 vaccines were introduced, several case reports described the link between COVID-19 vaccination and VZV reactivation. In our study we aimed to investigate how often patients developed VZV reactivation after mRNA COVID-19 vaccine compared to influenza vaccine. METHODS: We used the TriNetX platform and its global health research network containing aggregated de-identified information of electronic health records on over 100 million patients from scores of healthcare organizations. Three patient groups were identified: Patients receiving their 1(st) mRNA COVID-19 vaccine 12/20/2020-12/20/2022 Patients receiving their 2(nd) mRNA COVID-19 vaccine 12/20/2020-12/20/2022 Patients receiving influenza vaccine 12/20/2018-12/20/2022 Propensity Score Matching was used for age, gender, and Zoster vaccine status. We examined the prevalence of VZV reactivation in each group during the first 21 days following vaccination. RESULTS: Out of 444,016 patients in each matched group receiving either their 1(st) mRNA COVID-19 vaccine or the Influenza vaccine, 0.04% in the COVID-19 vaccine group and 0.15% in the influenza group, odds ratio (OR) 0.24 (95% CI 0.20-0.29), were diagnosed with VZV reactivation within 21 days. Among 445,382 patients in each matched group receiving either their 2(nd) mRNA COVID-19 vaccine or their influenza vaccine, 0.04% in the COVID-19 vaccine group and 0.13% in the Influenza group, OR 0.27 (95% CI 0.22-0.32), were diagnosed with VZV reactivation within 21 days. There was a lower risk of VZV reactivation after 1(st) or 2(nd) dose of mRNA COVID-19 vaccine than influenza vaccine. CONCLUSION: The risk of VZV reactivation after the 1(st) or 2(nd) dose of mRNA COVID-19 vaccination is smaller than VZX reactivation after influenza vaccine. The risk of VZV reactivation after mRNA COVID-19 vaccine is very low and hesitance to receive COVID-19 vaccine due to concern of VZV reactivation is not substantiated. DISCLOSURES: David C. Kaelber, MD, PhD, MPH, FAAP, FACP, FACMI, FAMIA, Becton, Dickinson and Company: Advisor/Consultant|Dynavax Technologies Corporation: Advisor/Consultant|Merck Sharp & Dohme Corporation: Advisor/Consultant