Maltezou, Helena C.

Background: COVID-19 vaccines are safe and effective at preventing severe disease. Among the rare complications that may compromise vaccine acceptance are allergic reactions. This study aimed at comparing the incidence and potential triggers of the most commonly reported allergic reactions related to licensed COVID-19 vaccines in Europe and the United States (US) based on data of the two of the world’s largest vaccine adverse event reporting systems, EudraVigilance and VAERS. Methods: Data pertaining to allergic reactions post COVID-19 vaccination reported from week 52/2020 to week 39/2021 were collected from EudraVigilance and VAERS databases and analyzed. Incidence rates were calculated using the corresponding administered vaccine doses as denominators for all licensed vaccines and both platform types (mRNA or vectored). The composition of the novel mRNA and vectored vaccines was examined to identify potential allergic triggers. Results: Anaphylactic reactions and anaphylactic shock were the most common allergic reactions, predominantly reported by females, at estimated incidence rates of 9.91/million and 1.36/million vaccine doses, respectively. A 2- to 5-fold higher incidence of both allergic reactions was found in Europe compared to the US for both vaccine platforms. Most cases were benign. Fatalities were extremely rare and associated with vectored rather than mRNA vaccines. Conclusions: The precise mechanism(s) for allergic reactions after vaccination with COVID-19 vaccines are not fully known. Plausible explanations include exposure to components of the final pharmaceutical product and cross-reactivity to ingredients or unintentional impurities in the final formula. Additional research is warranted to further improve vaccine safety.

Health-care providers (HCPs) are at increased risk for exposure to vaccine-preventable diseases (VPDs) in the workplace. The rationale for immunization of HCPs relies on the need to protect them and, indirectly, their patients from health-care-associated VPDs. Published evidence indicates significant immunity gaps for VPDs of HCPs globally. Deficits in knowledge and false perceptions about VPDs and vaccines are the most common barriers for vaccine uptake and may also influence communication about vaccines between HCPs and their patients. Most countries have immunization recommendations for HCPs; however, there are no universal policies and significant heterogeneity exists between countries in terms of vaccines, schedules, frame of implementation (recommendation or mandatory), and target categories of HCPs. Mandatory influenza immunization policies for HCPs have been implemented with high vaccine uptake rates. Stronger recommendations for HCP immunization and commitment at the level of the health-care facility are critical in order to achieve high vaccine coverage rates. Given the importance to health, mandatory immunization policies for VPDs that can cause serious morbidity and mortality to vulnerable patients should be considered.