Summary of the NACI Supplemental Statement on Mammalian Cell Culture-Based Influenza Vaccines

Mammalian cell culture-based technology is an innovative technique for influenza vaccine manufacturing that may be a valuable alternative to overcome some of the problems and vulnerabilities associated with conventional egg-based influenza vaccine production. Flucelvax^® Quad (Seqirus, Inc.) is the first and only mammalian cell culture-based quadrivalent inactivated, subunit influenza vaccine (IIV4-cc) authorized for adult and pediatric use in Canada. The National Advisory Committee on Immunization (NACI) has not previously made a recommendation on cell culture-based influenza vaccines in any population.

To review the available evidence for the efficacy, effectiveness, immunogenicity, and safety of IIV4-cc, and to summarize the NACI recommendation regarding the use of Flucelvax Quad in Canada in adults and children.

A systematic literature review on the vaccine efficacy, effectiveness, immunogenicity and safety of IIV4-cc in persons four years of age and older was performed. The systematic review's methodology was specified a priori in a written protocol. The NACI evidence-based process was used to assess the quality of eligible studies, summarize and analyze the findings, and develop a recommendation regarding the use of Flucelvax Quad in adults and children. The proposed recommendation was then considered and approved by NACI in light of the available evidence.

Thirteen eligible studies were included in the evidence synthesis. In the four observational studies that assessed vaccine effectiveness of IIV4-cc, there were some data indicating potentially improved protection against influenza compared to conventional egg-based quadrivalent inactivated influenza vaccines (IIV4) or trivalent inactivated influenza vaccine (IIV3), particularly against A(H3N2) virus infection. There was also some evidence that IIV4-cc may be more effective than egg-based trivalent or quadrivalent influenza vaccines against non-laboratory confirmed influenza-related outcomes, but there is insufficient evidence for laboratory-confirmed outcomes. Two randomized controlled trials assessed the immunogenicity and safety of IIV4-cc compared with mammalian cell culture-based trivalent inactivated, subunit influenza vaccine (IIV3-cc). The IIV4-cc was well-tolerated and the reported solicited local and systemic adverse events were generally mild to moderate in intensity, self-limited and did not precipitate sequelae. One clinical review of cases and six peer-reviewed randomized controlled trials (four in adults and two in children) that reported on the safety of IIV3-cc were included in the review. The evidence on immunogenicity and safety was consistent across these studies and showed that there was no significant difference in adults and children four years of age and older who had received IIV3-cc or an egg-based IIV3.

NACI concluded that there is fair evidence (Grade B Evidence) that Flucelvax Quad is effective, safe, and has non-inferior immunogenicity to comparable vaccines, based on direct evidence in adults and children nine years of age and older. NACI recommends that Flucelvax Quad may be considered among the IIV4 offered to adults and children nine years of age and older (Discretionary NACI Recommendation).