Impact of Covid-19 Vaccination on Spontaneous Pharmacovigilance Reporting in France

Introduction: In 2021, the massive Covid-19 vaccination campaign in France was accompanied by an intensified pharmacovigilance monitoring of their potential adverse drug reactions. The importance of this reporting might have led to an important selective reporting and overloading of Pharmacovigilance Centres, delaying the recording of some reports in the national pharmacovigilance database. In this context, we aimed to evaluate the impact of the Covid-19 vaccination campaign in France and related reports on spontaneous reporting of adverse drug reactions that were not related to the Covid-19 vaccine.Methods: We performed time-series analyses considering the monthly number of adverse drug reactions reported between January 1, 2018 and April 30, 2022 using the French Pharmacovigilance database. The impact of the Covid-19 vaccination campaign on the monthly reporting not Covid-19 vaccine related was estimated using interrupted time-series. January 2021, marking the start of the campaign, was the intervention date in the models. Analyses were run globally first considering all adverse drug reaction reports, and second according to notifier type and to case seriousness.Results: We included 170,294 reports registered in the French Pharmacovigilance database between January 1, 2018 and April 30, 2022 that were not Covid-19 vaccine-related. Among these, 77,067 (45.3%) were serious and 146,683 (86.1%) had been reported by health care professionals. The campaign start was associated with a nearly 35.0% decrease in average monthly reporting that was not Covid-19 vaccine-related, with a significant level decrease in the monthly number of reports of -658.0 (p < 10(-3)) immediately after the vaccination campaign start and a subsequent slope decrease of -50.0 (p < 10(-3)). This decrease was mainly due to a significant level and slope decrease (level: -739.2 p < 10(-3); slope: -39 [p < 10(-2)]) for health care professional reports. A similar level decrease was found for the monthly number of both serious and non-serious reports (-402.3, p < 10(-3); and -311.9, p = 10(-2), respectively). According to the ATC 1 level, the decrease in the monthly number of reports showed similar patterns for all drugs. However, a potential increase in the number of serious reports suspecting antineoplastic and immunomodulating drugs (ATC L) or drugs targeting blood was observed (ATC B).Conclusion: Our study showed a significant impact of the Covid-19 campaign vaccination in the reporting of adverse drug reactions that were not Covid-19 vaccine-related, of roughly 35%. This leads to a loss of information regarding the monitoring of drug safety that could have impacted the system capacity to detect safety signals for drugs other than Covid-19 vaccines.(c) 2023. The Author(s), under exclusive licence to Springer Nature Switzerland AG.