Immunogenicity and Safety of 2 Doses of Avian Influenza A (H5N1) Vaccine Administered 3 vs. 8 Weeks Apart

Given the recent circulation of avian influenza A(H5N1) clade 2.3.4.4b strains in birds and mammals in North America, Canada procured a supply of Arepanrix™ H5N1 for potential use in persons at high risk of highly pathogenic avian influenza exposure. This vaccine received regulatory approval in 2013, to be given in two doses at least 3 weeks apart. There is limited data on the effect of various intervals between the two doses on immunogenicity and tolerability. In this study two intervals between doses will be compared (3 vs. 8 weeks apart).

NCT Number	NCT07275060
Lead Sponsor	Canadian Immunization Research Network Collaborators: Dalhousie University, IWK Health Centre, Public Health Agency of Canada (PHAC), Canadian Center for Vaccinology, CHU de Quebec-Universite Laval, Vaccine Evaluation Center, Canada, McGill University Health Centre/Research Institute of the McGill University Health Centre
Conditions	H5N1 Influenza, H5N1 Virus, Avian Influenza, Avian Influenza A Virus
Enrollment	312 participants
Start Date	2025-10-14
Primary Completion	2027-02-28 (estimated)
Study Completion	2027-09-30 (estimated)
Updated on ClinicalTrials.gov	2026-01-16