Adverse Reactions Associated with Comirnaty® Among Healthcare Professionals: A Cohort Event Monitoring Study in a Portuguese Hospital: An International Journal of Medical Toxicology and Drug Experience

ABSTRACT

Introduction: The Portuguese government put into practice a vaccination plan soon after the approval of the first COVID-19 vaccine, prioritizing healthcare professionals (HCPs) and other population groups at risk. Objective: To characterize the case reports of adverse drug reactions (ADRs) associated with the administration of Comirnaty to HCPs in a Portuguese oncology hospital (IPO Coimbra). Methods: This study was a nine-month prospective, observational study following a cohort event monitoring approach focused on signalling ADRs associated with the administration of Comirnaty to HCP in IPO Coimbra. The case reports of ADRs were sent to the Pharmacovigilance Unit of Coimbra (UFC) between 14/01/2021 and 13/10/2021. The population of HCP was characterized according to gender and age distribution. The seriousness of ADRs was assessed for each individual case in accordance with WHO criteria [1]. ADRs were coded with MedDRA version 24.0 (System Organ Classification [SOC] and Preferred Term [PT]). ADRs were classified as expected or unexpected according to their description in the Summary of Product Characteristics (SmPC) of Comirnaty [2]. Results: A total of 816 HCPs were inoculated with at least one dose of Comirnaty. The case reports of ADRs concerned 469 (57.5%) HCPs 386 (82.3%) females;642 (78.7%) aged 30-59 years old. Of the 469 case reports, 24 (5%) were assessed as serious, 44 (9.4%) as unexpected, and 11 (2.3%) as both serious and unexpected. The 469 case reports contained a total of 1,955 ADRs. "General disorders and administration site condition" (n = 1,075;54,9%), such as vaccination site pain, chills and vaccination site swelling;"Musculoskeletal and connective tissue disorders" (n = 373;19.1%), including myalgia and arthralgia;and "Nervous system disorders" (n = 250;12.8%), including headache, were the most frequently reported ADRs, which is in line with the SmPC of Comirnaty®. The 11 case reports classified as both serious and unexpected contained a total of 17 ADRs, including hyperhidrosis and paraesthesia. Conclusion: The results of this study bring value to the characterization of the safety profile of Comirnaty® since the use of a cohort of individuals allows to estimate frequencies of ADRs in the real-world. Further, serious, and unexpected ADRs were identified. Importantly, this type of safety data was further included in the SmPC of the vaccine. In conclusion, the results are in favour of the positive benefitrisk ratio of Comirnaty®, and reinforce the importance of post-marketing pharmacovigilance to increase knowledge on drug safety.