| Summary: | Russian health care workers currently use trivalent influenza vaccines with a strain of a single lineage of type B virus. The purpose of our study was to evaluate the immunogenicity of an adjuvanted quadrivalent inactivated subunit influenza vaccine Grippol Quadrivalent in pediatric population 6 to 17 years old. We compared this new vaccine to a trivalent Grippol Plus vaccine in terms of immunogenicity against certain strains of influenza virus. A multicenter double-blind randomized controlled clinical study was conducted in 440 pediatric subjects (age groups: 6 to 11; 12 to 17 y.o.); 221 subjects received Grippol Quadrivalent, 219 – Grippol Plus. Vaccine immunogenicity was evaluated by seroprotection rate (SPR), seroconversion rate (SCR), geometric mean titer (GMT) of antibodies, and an X-fold rise in antibodies level (↑GMT). Antibodies quantification was done using hemagglutination inhibition assay (HAI) in serial serum dilutions. No significant differences were found between the two vaccines’ performance against A(H1N1), A(H3N2) strains or Victoria B virus. With respect to type A virus, both vaccines satisfied three of CPMP criteria (SPR, SCR, ↑GMT). With respect to Victoria B virus, the two vaccines met but one CPMP criterion (↑GMT). The immunogenicity against Yamagata B virus was evaluated only for Grippol Quadrivalent vaccine which met two of CPMP requirements (SCR, ↑GMT). Our findings suggest that in terms of its prophylactic efficiency, Grippol Quadrivalent vaccine is no inferior to the Grippol Plus one.
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