400
Participants
Start Date
November 18, 2016
Primary Completion Date
September 30, 2025
Study Completion Date
September 30, 2026
Inactivated influenza vaccine (NH formulation)
Round 1 (November): 0.5mL FluQuadri®, Sanofi Pasteur, containing 60μg antigen - 15μg for each influenza strain included - with strains recommended by the WHO for the northern hemisphere formulation
Inactivated influenza vaccine (SH formulation)
Round 2 (May): 0.5mL Vaxigrip®, Sanofi Pasteur, containing 45μg antigen - 15μg for each influenza strain included - with strains recommended by the WHO for the southern hemisphere formulation
Placebo
Round 2 (May): 0.5mL normal saline
The University of Hong Kong, Hong Kong
Centers for Disease Control and Prevention
FED
Hospital Authority, Hong Kong
OTHER_GOV
The University of Hong Kong
OTHER