(A53) Safety monitoring of COVID-19 vaccines in multiple European countries: initial results from the COVID-19 Vaccine Monitor (CVM)

Publication Number: 336

Background: The roll-out of the novel COVID-19 vaccines in a large population across multiple countries called for comprehensive monitoring of the safety of these vaccines. The multi-country implementation of a cohort event monitoring study with a common protocol and pooled data shared in real-time provides additional monitoring.

Objectives: To report real-time incidence rates of adverse events following immunization (AEFI), serious adverse reactions, and adverse events of special interest (AESI) after receiving one or more EMA-approved COVID-19 vaccines doses.

Methods: A prospective cohort event monitoring study was conducted in 13 European countries to monitor the safety of first, second, and booster doses of the EMA-approved COVID-19 vaccines in both the general population and clinical subgroups of special interest (children/adolescents, pregnant, lactating, immunocompromised, prior SARS-CoV2 infection and allergy). Participants can be included in more than one subset. Participants registered online within two days of receiving the vaccine and reported demographic data, medical history, and AEFI up to six months after vaccination. Incidence rates were calculated for all AEFI after the first and second dose for the general population and for the first booster in the population of special interest.

Results: 642292 participants were included between 20 December 2020 and 30 September 2022 in the general population subset receiving dose 1; 466010 (72.6%) provided follow-up data after dose 2. Of the 642292 general population participants, 495383 (77.1%) and 381876 (81.9%) reported experiencing at least one AEFI after dose 1 and 2, respectively. Only 2001 (0.3%) participants reported experiencing at least one AESI after dose 1 and 1522 (0.3%) after dose 2. A total of 3142 (0.5%) participants reported at least one serious adverse event after dose 1 and 1697 (0.4%) after dose 2. The special interest subgroups included 2513 participants; 127 children ( 5.1%), 351 pregnant (14.0%), 123 lactating (4.9%), 889 prior SARS-CoV2 infection (35.4%), 205 immunocompromised ( 8.2%) and 818 allergy (32.6%). Of these subgroups, participants reported experiencing at least one adverse event (respectively 50, 39.4%; 200, 57.0%; 97,78.9%; 605,68.1%; 128,62.4%; 622,76.0%) after the booster dose.

Conclusions: While a majority of the participants reported experiencing at least one AEFI after vaccination, only a small proportion was considered an AESI or serious event. This is in line with the data reported from clinical trials and other cohort event monitoring studies. A common data model has been developed for further analysis of reported events, comparisons between groups, and confounding.