Immunogenic Properties and Safety of a Quadrivalent Inactivated Subunit Adjuvanted Influenza Vaccine in Adults Aged 18 to 85 Years at the End of the COVID-19 Pandemic in the 2022–2023 Season

Kostinov, Mikhail P.; Kostinova, Aristitsa M.; Iushkova, Sofia; Gladkova, Lilia; Vlasenko, Anna; Dagil, Yulia; Kvasova, Maria; Kameleva, Anastasia; Kachnova, Anastasia; Solovеva, Irina; Khamidulina, Anna; Prutskova, Ekaterina; Mekhantseva, Irina; Andreeva, Natalia; Polishchuk, Valentina B.; Mana, Yvette Albahansa; Kostinov, Anton M.

doi:10.3390/vaccines14020181

Open AccessArticle

Immunogenic Properties and Safety of a Quadrivalent Inactivated Subunit Adjuvanted Influenza Vaccine in Adults Aged 18 to 85 Years at the End of the COVID-19 Pandemic in the 2022–2023 Season

by

Mikhail P. Kostinov

^1,2

,

Aristitsa M. Kostinova

^1,3

,

Sofia Iushkova

¹,

Lilia Gladkova

³,

Anna Vlasenko

⁴

,

Yulia Dagil

⁵

,

Maria Kvasova

⁶

,

Anastasia Kameleva

^3,7

,

Anastasia Kachnova

³,

Irina Solovеva

⁸,

Anna Khamidulina

⁸,

Ekaterina Prutskova

⁸,

Irina Mekhantseva

^9,*

,

Natalia Andreeva

^10,11,

Valentina B. Polishchuk

²,

Yvette Albahansa Mana

¹ and

Anton M. Kostinov

²

¹

Department of Epidemiology and Modern Vaccination Technologies, I. M. Sechenov First Moscow State Medical University (Sechenov University), Moscow 119991, Russia

²

I. I. Mechnikov Research Institute of Vaccines and Sera, Moscow 105064, Russia

³

Moscow Health Department, D. D. Pletnev City Clinical Hospital, Moscow 105077, Russia

⁴

Federal State Budgetary Educational Institution of Higher Education, Samara State Medical University, The Ministry of Healthcare of the Russian Federation, Samara 443079, Russia

⁵

National Research Center, Institute of Immunology of the Federal Medical Biological Agency of Russia, Moscow 115522, Russia

⁶

Federal State Budgetary Educational Institution of Higher Education, Privolzhsky Research Medical University, Ministry of Health of the Russian Federation, Nizhniy Novgorod 603005, Russia

⁷

Department of Clinical Immunology, Allergology and Adaptology, P. Lumumba Russian University of Peoples’ Friendship, Moscow 117198, Russia

⁸

Department of Pediatrics, Institute of Medicine, Ecology and Physical Culture, Ulyanovsk State University, Federal State Budgetary Educational Institution of Higher Education, Ulyanovsk 432007, Russia

⁹

Department of Internal Medicine, Karaganda Medical University, Karaganda 100012, Kazakhstan

¹⁰

Department of Healthcare Management and Economics, The Chuvash State University Named After I. N. Ulyanov, Federal State Educational Establishment of Higher Professional Education, Cheboksary 428015, Russia

¹¹

Budgetary Institution “City Children’s Clinical Hospital”, Ministry of Health of the Chuvash Republic, Cheboksary 428000, Russia

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Author to whom correspondence should be addressed.

Vaccines 2026, 14(2), 181; https://doi.org/10.3390/vaccines14020181

Submission received: 3 January 2026 / Revised: 6 February 2026 / Accepted: 11 February 2026 / Published: 14 February 2026

(This article belongs to the Section Vaccine Advancement, Efficacy and Safety)

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Abstract

Background: SARS-CoV-2 infection has raised concerns about altered immune responses, creating a need to evaluate influenza vaccine performance in the post-COVID period. This study aimed to compare the immunogenicity and safety of a quadrivalent inactivated subunit adjuvanted influenza vaccine in adults aged 18–85 years during the 2022–2023 season. Methods: A total of 144 adults were enrolled: group 1, aged 18–59 years (n = 124), and group 2, aged 60–85 years (n = 20). All received a quadrivalent inactivated subunit adjuvanted vaccine containing 5 μg of each influenza antigen and 500 μg of Azoximer bromide. IgG antibodies to vaccine strains were measured at baseline and days 30–32 using the hemagglutination inhibition assay. Participants were actively monitored for adverse events by telephone. Results: The Geometric Mean Fold Increase (GMFI) met the efficacy criteria in both age groups (≥2.5 for 18–59 years and ≥2.0 for 60–85 years), with no significant differences. The seroprotection rate reached accepted thresholds for most strains but was below criteria for B/Victoria in the 18–59 group (48%) and for B/Phuket in the 60–85 group (35%). Significant between-group differences were observed for B/Victoria (p = 0.01) and B/Phuket (p = 0.007). Seroconversion met criteria for all strains in younger adults, but for older adults, it was insufficient for B/Phuket (20%, below the ≥30% threshold; p = 0.05 vs. 18–59 years). Local reactions occurred in 24.2% and systemic in 11.3% of younger adults; in older adults, in 20% and 15%, respectively. All resolved spontaneously within 1–3 days. Conclusions: The quadrivalent adjuvanted influenza vaccine demonstrated acceptable immunogenicity and safety in adults aged 18–85 years despite potential post-COVID immune alterations.

Keywords: adults; SARS-CoV-2 infection; adjuvanted influenza vaccine; azoximer bromide; immunogenicity; influenza; vaccination

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MDPI and ACS Style

Kostinov, M.P.; Kostinova, A.M.; Iushkova, S.; Gladkova, L.; Vlasenko, A.; Dagil, Y.; Kvasova, M.; Kameleva, A.; Kachnova, A.; Solovеva, I.; et al. Immunogenic Properties and Safety of a Quadrivalent Inactivated Subunit Adjuvanted Influenza Vaccine in Adults Aged 18 to 85 Years at the End of the COVID-19 Pandemic in the 2022–2023 Season. Vaccines 2026, 14, 181. https://doi.org/10.3390/vaccines14020181

AMA Style

Kostinov MP, Kostinova AM, Iushkova S, Gladkova L, Vlasenko A, Dagil Y, Kvasova M, Kameleva A, Kachnova A, Solovеva I, et al. Immunogenic Properties and Safety of a Quadrivalent Inactivated Subunit Adjuvanted Influenza Vaccine in Adults Aged 18 to 85 Years at the End of the COVID-19 Pandemic in the 2022–2023 Season. Vaccines. 2026; 14(2):181. https://doi.org/10.3390/vaccines14020181

Chicago/Turabian Style

Kostinov, Mikhail P., Aristitsa M. Kostinova, Sofia Iushkova, Lilia Gladkova, Anna Vlasenko, Yulia Dagil, Maria Kvasova, Anastasia Kameleva, Anastasia Kachnova, Irina Solovеva, and et al. 2026. "Immunogenic Properties and Safety of a Quadrivalent Inactivated Subunit Adjuvanted Influenza Vaccine in Adults Aged 18 to 85 Years at the End of the COVID-19 Pandemic in the 2022–2023 Season" Vaccines 14, no. 2: 181. https://doi.org/10.3390/vaccines14020181

APA Style

Kostinov, M. P., Kostinova, A. M., Iushkova, S., Gladkova, L., Vlasenko, A., Dagil, Y., Kvasova, M., Kameleva, A., Kachnova, A., Solovеva, I., Khamidulina, A., Prutskova, E., Mekhantseva, I., Andreeva, N., Polishchuk, V. B., Mana, Y. A., & Kostinov, A. M. (2026). Immunogenic Properties and Safety of a Quadrivalent Inactivated Subunit Adjuvanted Influenza Vaccine in Adults Aged 18 to 85 Years at the End of the COVID-19 Pandemic in the 2022–2023 Season. Vaccines, 14(2), 181. https://doi.org/10.3390/vaccines14020181

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Immunogenic Properties and Safety of a Quadrivalent Inactivated Subunit Adjuvanted Influenza Vaccine in Adults Aged 18 to 85 Years at the End of the COVID-19 Pandemic in the 2022–2023 Season

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