Three seasons of enhanced safety surveillance of a cell culture-based
quadrivalent influenza vaccine
Abstract
Background: Enhanced safety surveillance (ESS) of seasonal influenza
vaccines is required by the European Medicines Agency (EMA). ESS is
conducted during each Northern Hemisphere (NH) influenza season and aims
to monitor the reactogenicity of influenza vaccines early in the season.
A cell culture-based quadrivalent influenza vaccine (QIVc; Flucelvax®
Tetra), which has an advantage of avoiding egg-adaptive mutations that
may reduce vaccine effectiveness, has been available in Europe since the
2019/20 influenza season. The objective of this manuscript is to
summarize ESS activity across three seasons for QIVc in all age groups.
Methods: As per EMA guidelines, an enhanced passive safety surveillance
(EPSS) approach was adopted. The EPSS envisages near-real-time
surveillance of adverse events (AEs) that are reported spontaneously by
vaccinees. The EPSS was conducted in primary care setting in Genoa
(Italy) during the seasons 2019/20, 2020/21 and 2021/22. All AEs
registered within the first 7 days following immunization were analyzed
by season, type, age group and seriousness. Results: Over three seasons,
a total of 3,603 QIVc exposures were recorded within EPSS. No safety
signals were identified. The overall reporting rates of individual case
safety reports (ICSRs) for the seasons 2019/20, 2020/21 and 2021/22 were
1.75% (18/1030), 0.48% (5/1032) and 0.40% (4/1001), respectively. The
average number of AEs per ICSR was similar (range 3.3–3.8) across the
three seasons. Most AEs were reactogenic in nature. The rate of AEs was
similarly low in all age groups. Conclusions: These results support the
favorable safety profile of QIVc in all indicated age groups.