Two severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) messenger RNA (mRNA) vaccines, tozinameran/BNT162b2 (Comirnaty®, Pfizer-BioNTech) and elasomeran/mRNA-1273 (Spikevax®, Moderna), were approved by the Food and Drug Administration (FDA) and the European Medicines Agency (EMA) at the end of 2020, less than a year after the start of the coronavirus disease 2019 (COVID-19) pandemic. In France, the health authorities have requested an intensive vaccination campaign, accompanied by a reinforced and active pharmacovigilance surveillance. This surveillance and analysis of real-life data, based on spontaneous reports received by the French Network of Regional PharmacoVigilance Centers (RFCRPV), has enabled to identify numerous pharmacovigilance signals. Some of them, such as myocarditis and heavy menstrual bleeding, have been confirmed as adverse effects of these vaccines.

We propose a descriptive review of the main pharmacovigilance signals identified by the RFCRPV concerning vaccines from the mRNA platform.

Most pharmacovigilance signals were common to both mRNA vaccines: myocarditis, menstrual disorders, acquired haemophilia, Parsonage-Turner syndrome, rhizomelic pseudo-polyarthritis and hearing disorders. Other signals were more specific, such as arterial hypertension with tozinameran or delayed reaction site injection with elasomeran.

This non-exhaustive review illustrates the experience of RFCRPV in identifying and monitoring pharmacovigilance signals related to mRNA vaccines in France during the COVID-19 pandemics, and the crucial role of pharmacological and clinical expertise in this area. It also highlights the predominant contribution of spontaneous reporting in the generation of pharmacovigilance signals, particularly for serious and rare adverse events not detected before marketing.