Seasonal dating meaning
Worldwide, these annual epidemics are estimated to result in about 3 to 5 million cases of severe illness, and about 290 000 to 650 000 deaths.
In industrialized countries most deaths associated with influenza occur among people age 65 or older (1).
Immunity from vaccination wanes over time so annual vaccination is recommended to protect against influenza.
Injected inactivated influenza vaccines are most commonly used throughout the world.
Illnesses range from mild to severe and even death.
Hospitalization and death occur mainly among high risk groups.
Patients with severe or progressive clinical illness associated with suspected or confirmed influenza virus infection (i.e.
clinical syndromes of pneumonia, sepsis or exacerbation of chronic underling diseases) should be treated with antiviral drug as soon as possible.
Safe and effective vaccines are available and have been used for more than 60 years.
The effects of seasonal influenza epidemics in developing countries are not fully known, but research estimates that 99% of deaths in children under 5 years of age with influenza related lower respiratory tract infections are found in developing countries (2).
In terms of transmission, seasonal influenza spreads easily, with rapid transmission in crowded areas including schools and nursing homes.
However, during periods of low influenza activity and outside of epidemics situations, the infection of other respiratory viruses e.g.
rhinovirus, respiratory syncytial virus, parainfluenza and adenovirus can also present as Influenza-like Illness (ILI) which makes the clinical differentiation of influenza from other pathogens difficult.