Annually, influenza causes 650 000 fatalities, 3 to 5 million severe cases, and affects over 1 billion people worldwide, making it one of the world's top causes of morbidity and mortality.1 The influenza pandemic is considered one of the 10 main threats facing global public health.1 In addition, influenza affects 5–10% of adults and 20–30% of children worldwide.2 Influenza viruses undergo continuous genetic alterations, resulting in modest antigenic changes known as 'antigenic drift', necessitating routine updates of seasonal influenza vaccines.