Hesitancy and reactogenicity to mRNA-based COVID-19 vaccines–Early experience with vaccine rollout in a multi-site healthcare system

BACKGROUND: Hesitancy and incomplete vaccination against coronavirus disease 2019 (COVID-19) remains an obstacle to achieving herd immunity. Because of fear of vaccine reactions, patients with medical and allergic co-morbidities express heightened hesitancy. Limited information is available to guide these patients. We sought to identify factors associated with mRNA-based COVID-19 vaccines hesitancy and reactogenicity. METHODS: We surveyed employees of a multi-site health system in central Pennsylvania who were offered the COVID-19 vaccine (N = 18,740) inquiring about their experience with the Moderna and Pfizer-BioNTech mRNA-based vaccines. The survey was administered online using the REDCap platform. We used multivariable regression analysis to determine whether a particular factor(s) (e.g., demographics, selected co-morbid allergic and medical conditions, vaccine brand, and prior COVID-19) were associated with vaccine reactogenicity including the occurrence and severity of local and systemic reactions. We also explored factors and reasons associated with vaccine hesitancy. RESULTS: Of the 5709 who completed the survey (response rate, 30.4%), 369 (6.5%) did not receive the vaccine. Black race and allergy to other vaccines were associated with vaccine hesitancy. Reaction intensity following the first vaccine dose and allergic co-morbidities were associated with incomplete vaccination. Older individuals (>60 years) experienced less reactogenicity. Females had higher odds of local and systemic reactions and reported more severe reactions. Asians reported more severe reactions. As compared to Pfizer-BioNTech, the Moderna vaccine was associated with higher odds of vaccine reactions of higher severity. Prior COVID-19 resulted in more severe reactions following the first dose, but less severe reactions following the second dose. CONCLUSIONS: Targeted campaigns to enhance vaccination acceptance should focus on Black individuals, females, and those with allergic co-morbidities. Prior COVID-19 caused more severe reactions after the first but not the second vaccine dose. Moderna vaccine caused more vaccine reactions. Lessons learned from the early rollout of COVID-19 vaccine may serve to inform future novel vaccine experiences.