Cohort Event Monitoring of COVID-19 Vaccine Safety in Special Cohorts in Italy

ABSTRACT

Introduction: Marketed COVID-19 vaccines showed an overall favourable safety profile in pivotal trials. However, those trials did not include high risk/fragile patient categories;hence, close monitoring of COVID-19 vaccine safety in those special cohorts in real-world setting is needed. The European Medicines Agency-funded "Covid- Vaccine-Monitor" project was set up to prospectively measure the incidence of solicited/unsolicited adverse events following COVID- 19 vaccination in several European Countries as reported by vaccinees through web-based questionnaires. Italy is one of the Countries participating in the project as a large network named "ilmiovaccinocovid19 collaborating group". Objective(s) To measure the incidence of vaccinee-reported adverse events following immunization (AEFIs) with marketed COVID-19 vaccines in pregnant and lactating women, pediatrics, immunocompromised, people with history of allergy and people with prior SARSCoV- 2 infection in Italy. Method(s) We performed a prospective cohort study of the abovementioned categories of vaccinees, who were recruited at multiple vaccination centers within 48 hours from either the first or booster COVID-19 vaccine dose administration. After providing informed consent and get registered into the web-app, vaccinees were asked to fill in an electronic baseline questionnaire and 6 follow-up questionnaires at different time points, within 6-month from vaccine administration, in which information on potential vaccine-related AEFIs were collected. We explored and compared the frequency of local and systemic solicited adverse events following first or booster dose for each special cohort and vaccine brands. Result(s) Overall, 1,331 vaccinees (40.4% first dose and 59.6% booster dose) were included in the analysis. Of these, 8.4% were immunocompromised, 32.0% had history of allergy, 25.5% had prior SARS-CoV-2 infection, 23.4% were children/adolescents, 6.2% were pregnant and 4.6% were lactating women (non-mutually exclusive cohorts). Of subjects belonging to at least one cohort, 52.3% reported at least one AEFI following either the first or booster dose. Among all special cohorts, injection site pain was the most frequently reported solicited local AEFI, after both the first (37.5%) and booster (39.5%) dose. As solicited systemic AEFIs, headache (19.0%) was the most frequently reported after the first dose, while malaise (23.7%) and fatigue (23.7%) after the booster dose. The frequency of severe AEFIs was very low following both first dose (0.8%) and booster dose (0.6%). Conclusion(s) Overall, this study confirmed the favourable safety profile of COVID-19 vaccines also in the above-mentioned special categories who have not (or marginally) been included in pivotal trials.