L’National Agency for the Safety of Medicines and Health Products (ANSM) has published pharmacovigilance data [1, 2] relating to BEYFORTUS 50 mg and 100 mg solution for injection in pre-filled syringe (nirsevimab).
These data were collected in France during the first prevention campaign against respiratory syncytial virus (RSV) infections in newborns and infants, which began in September 2023.
The analysis takes into account all pharmacovigilance data collected in the national pharmacovigilance database (BNPV) and by the laboratory marketing BEYFORTUS (Sanofi Pasteur).
A majority of the statements relate to the effectiveness
Between September 11, 2023 and April 30, 2024, 244,495 doses of BEYFORTUS were delivered to maternity hospitals and towns.
The pharmacovigilance report concerns the analysis of 198 pharmacovigilance cases declared during these 8 months.
The vast majority (74.7%) of these cases reported in pharmacovigilance report less effectiveness or ineffectiveness of BEYFORTUS, resulting in the appearance of RSV bronchiolitis despite the injection of the antibody. monoclonal. No particular risk factors have been identified in these children. The bronchiolitis developed despite the BEYFORTUS injection was of variable severity. No deaths linked to these bronchiolitis have been recorded.
Three signals to evaluate and adverse events to monitor
This first monitoring of adverse effects made it possible to highlight three pharmacovigilance signals with a risk:
- respiratory disorder outside of an infectious context such as dyspnea, desaturation, respiratory pause of suggestive chronology, which may be compatible with postinjection immunogenicity: signal of moderate strength and severe risk;
- systemic effects such as influenza syndrome, reduced food intake, hypotonia, which can also be compared to postinjection immunogenicity: signal of moderate strength and low risk;
- of stroke: signal of weak strength and severe risk (isolated case and risk of stroke described perinatally).
Three cases of sudden death are reported without identified signal to date (there have been no further deaths during the follow-up period). Despite the absence of data in the literature, signals in this report, or in international data, the occurrence of possible new cases of sudden death remains closely monitored.
The other cases report expected effects (reactions at the injection site, skin reactions, fever).
In addition to the signals and possible new cases of sudden death, adverse events should be monitored:
- immunoallergic reactions;
- the possible emergence of cases of resistance;
- petechiae (in the context of a theoretical risk of thrombocytopenia).
Note that several medication errors (administration of a higher dose or misuse with use outside of recommendations) have been reported without clinical consequences identified to date. These situations require particular vigilance.
Continuation of the pharmacovigilance investigation
This first monitoring report of adverse effects reported with BEYFORTUS confirms the positive benefit/risk balance of this medicine as part of its indication and in the targeted population through the countryside.
A second report on the current immunization campaign should make it possible to better identify serious or unexpected adverse effects, and to better evaluate the signals identified in the first report. In addition, in this second upcoming report, it is proposed to limit the analysis of cases of RSV bronchiolitis associated with ineffectiveness to relevant cases (significant cases, vital prognosis or possible death).
