Comparison of immunogenicity between candidate influenza A(H3N2) virus vaccine strains in Japan: A randomized controlled trial using a monovalent vaccine of A/Saitama/103/2014 (CEXP-002) and A/Hong Kong/4801/2014 (X-263). Issue 42 (29th September 2020)

• Record Type: Journal Article
• Authors: Kase, Tetsuo; Inoue, Megumi; Morikawa, Saeko; Kumashiro, Hiroko; Hiroi, Satoshi; Nakata, Keiko; Ito, Kazuya; Ishibashi, Motoki; Tsuru, Tomomi; Irie, Shin; Maeda, Akiko; Ohfuji, Satoko; Fukushima, Wakaba; Hirota, Yoshio
• Is Part Of: Vaccine. Volume 38:Issue 42(2020)
• Page Start: 6524
• Page End: 6532
• Publication Date: 2020-09-29
• Subjects: Influenza A(H3N2) vaccine strains -- Immunogenicity -- Antigenic matching -- Randomized controlled trial; WHO World Health Organization -- NIID National Institute of Infectious Diseases -- MHLW Ministry of Health, Labour and Welfare -- HA hemagglutinin -- HI hemagglutination inhibition -- TCID50 50% tissue culture infectious doses -- CPE cytopathic effect -- GMT geometric mean titer -- MFR mean fold rise -- SCP seroconversion proportion -- SPP seroprotection proportion -- SD standard deviation; Vaccines -- Periodicals; 615.372
• DOI: 10.1016/j.vaccine.2020.08.025
• Languages: English
• ISSNs: 0264-410X

Abstract

Highlights: Two A(H3N2) influenza vaccine strains were compared in terms of immunogenicity. The antigenically unmatched strain to epidemic strains induced higher immunogenicity. Immunogenicity is more important than antigenicity for vaccine strain selection. Abstract: Background: For the 2017–18 influenza season, A/Saitama/103/2014 (CEXP-002) (Saitama strain) was antigenically more similar to prior circulating strains than A/Hong Kong/4801/2014 (X-263) (Hong Kong strain) in a ferret model and was selected as the A(H3N2) vaccine virus strain in Japan. However, the Saitama strain grew poorly, and the Japanese government switched to the Hong Kong strain, raising public concerns of poor effectiveness. To enhance understanding of the correlation between antigenicity in experimental models and immunogenicity, as a surrogate measure of vaccine effectiveness, in the human population, we compared the immunogenicity of specially-prepared single dose monovalent influenza A(H3N2) vaccines containing the Saitama or the Hong Kong strain. Methods: A randomized controlled trial of 100 healthy adults aged 20–64 years (n = 50/group) was conducted. Virus neutralization assay was performed on sera from days 0 (pre-vaccination) and 21 (post-vaccination). Geometric mean titer (GMT), mean fold rise (MFR), seroconversion proportion (SCP), and seroprotection proportion (SPP) were calculated for vaccine strains and a representative circulating A(H3N2) virus strain (A/Osaka/188/2017). Results: For the Hong Kong strain, post-vaccination GMT was significantly higher in the Hong Kong vaccine recipients (1:546 vs 1:260, p < 0.01), but MFR, SCP, and SPP were similar for both vaccine groups. For the Saitama strain, post-vaccination GMT (1:116 vs 1:61, p = 0.01) and SPP (86% vs 68%, p = 0.03) were significantly higher in the Hong Kong vaccine recipients, but MFR and SCP were similar for both vaccine groups. Against A/Osaka/188/2017, post-vaccination GMT and MFR were similar in both vaccine groups, but SCP (32% vs 4%, p < 0.01) and SPP (28% vs. 6%, p < 0.01) were significantly higher in the Hong Kong vaccine recipients. Conclusion: The Hong Kong vaccine induced better or equivalent immunogenicity in comparison to the Saitama vaccine. Our trial showed that antigenic similarity in experimental models does not necessarily correlate with immunogenicity in the human population. Clinical trial registration : UMIN000029293.