Seasonal influenza is an acute respiratory infection caused by influenza viruses which circulate in all parts of the world. It is a serious condition that can lead to severe complications such as heart attacks and strokes and has a huge human, societal and economic impact.
Flu is a contributing factor to five out of the top 10 deaths globally with 3 to 5 million severe influenza cases reported worldwide. The WHO estimates that flu may be responsible for an estimated 290,000 to 650,000 respiratory deaths per year worldwide, with a global burden of about 10 million influenza-related hospitalizations every year.
According to a recent study, one is 10 times more likely to have a heart attack in the week after being diagnosed with the flu and eight times more likely to have a stroke. People over 65 years of age are most susceptible to flu and its complications, because the immune system deteriorates with age (immunosenescence) and experience a higher risk of influenza-associated morbidity and mortality. 50-70% of hospitalizations occur in people aged over 65 and 70-85% of flu-related deaths occur in this age group.