Immunogenicity and Safety of AS03-adjuvanted H5N1 Influenza Vaccine in Children 6-35 Months of Age: Results From a Phase 2, Randomized, Observer-blind, Multicenter, Dose-ranging Study.

Joon Hyung Kim, Mamadou Drame, Thanyawee Puthanakit, Nan-Chang Chiu, Khuanchai Supparatpinyo, Li-Min Huang, Cheng-Hsun Chiu, Po-Yen Chen, Kao-Pin Hwang, Jasur Danier, Damien Friel, Bruno Salaun, Wayne Woo, David W Vaughn, Bruce Innis, Anne Schuind

Journal: The Pediatric infectious disease journal 2022;40(9):e333-e339

PMID: 34285165

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Abstract

BACKGROUND

This phase 2 observer-blind, randomized, multicenter, dose-ranging study evaluated immunogenicity and safety of different formulations of an AS03-adjuvanted H5N1 influenza vaccine in children 6-35 months of age.

METHODS

One hundred eighty-five children randomized into 5 groups [1.9 µg hemagglutinin (HA)/AS03B, 0.9 µg HA/AS03C, 1.9 µg HA/AS03C, 3.75 µg HA/AS03C or 3.75 µg HA/AS03D] were to receive 2 doses administered 21 days apart (primary vaccination). AS03 was classified by amount of DL-α-tocopherol, with AS03B the highest amount. One year later, all subjects were to receive unadjuvanted 3.75 µg HA as antigen challenge. Immunogenicity was assessed 21 days after primary vaccination (day 42) and 7 days after antigen challenge (day 392). Immunogenicity-fever index, based on hemagglutination inhibition and microneutralization antibody titers at day 42 and fever 7 days after each vaccination, was used to guide the selection of an acceptable formulation.

RESULTS

After primary vaccination, formulations elicited strong homologous immune responses with all subjects' hemagglutination inhibition titers ≥1:40 post-vaccination. Immunogenicity-fever index based on hemagglutination inhibition and microneutralization assays showed that 1.9 µg HA/AS03B ranked the highest. Antibody levels persisted >4 times above baseline 12 months after primary vaccination with all formulations (day 385). Antibodies increased >4-fold after antigen challenge (day 392/day 385) with 1.9 µg HA/AS03B, 0.9 µg HA/AS03C and 1.9 µg HA/AS03C formulations. Overall per subject, the incidence of fever ranged from 28.6% (3.75 µg HA/AS03D) to 60.5% (1.9 µg HA/AS03B).

CONCLUSIONS

All formulations were highly immunogenic and demonstrated acceptable safety profiles, with the 1.9 µg HA/AS03B providing the most favorable balance of immunogenicity versus reactogenicity for use in children 6-35 months of age.

Address: From the Vaccines Clinical Research and Development, GSK, Rockville, Maryland.; Vaccine Biostatistics Department, GSK, Rockville, Maryland.; Department of Pediatrics, Center of Excellence in Pediatric Infectious Diseases and Vaccines, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.; Department of Pediatrics, Mackay Children's Hospital, Taipei, Taiwan.; Department of Internal Medicine, Chiang Mai University, Chiang Mai, Thailand.; Department of Pediatrics, National Taiwan University Hospital, Taipei, Taiwan.; Department of Pediatrics, Chang Gung Memorial Hospital, Chang Gung University Col-lege of Medicine, Taoyuan, Taiwan.; Department of Pediatrics, Taichung Veterans General Hospital, Taichung, Taiwan.; Division of Pediatric Infectious Diseases, China Medical University College of Medicine, Children's Hospital, Taichung, Taiwan.; Clinical and Epi Research and Development, GSK, Rockville, Maryland.; GSK, Wavre, Belgium.; Clinical Laboratory Sciences, GSK, Rixensart, Belgium.; Biostatistics and Statistical Programming Department, GSK, Rockville, Maryland.; Vaccines Research and Development, GSK, Rockville, Maryland.; Center for Vaccine Innovation and Access, PATH, Washington, District of Columbia.; Vaccine Discovery and Development, GSK, Rockville, Maryland, USA.

DOI: 10.1097/INF.0000000000003247

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MeSH Terms: Adjuvants, Immunologic, Antibodies, Viral, Child, Preschool, Dose-Response Relationship, Immunologic, Female, Humans, Immunogenicity, Vaccine, Infant, Influenza A Virus, H5N1 Subtype, Influenza Vaccines, Influenza, Human, Male