Burden of the disease

    1. WHO _ Seasonal influenza 11/7/2020
    2. WHO Influenza (Seasonal) 6 November 2018

Is influenza really a severe disease?

Influenza is a severe disease, with 3 to 5 million severe cases reported worldwide each year. It can result in serious complications such as pneumonia, myocarditis, encephalitis, stroke and multi-organ failure1,2,3 Influenza is a contributing factor to 5 of the 10 top causes of death worldwide, including cardiovascular diseases, the leading cause of death globally3,4,5,6

Influenza is a highly contagious respiratory disease which can be contracted by both healthy and at-risk individuals. Elderly people (aged >70 years), people living with heart disease & diabetes are at higher risk of severe influenza related complications3,4,5,7

Acute illnesses such as influenza infection can contribute to functional decline and long-term disability. A study has shown that >30% of elderly patients had a worse functional status after hospitalization for acute medical illness, as caused by a new disability at discharge. Of those, only 30% functionally recovered after one year.8,9

Immediately following influenza infection, the risk of a heart attack is elevated six times in persons aged 35 years and older10 People living with diabetes are 3 times more likely to be hospitalized due to influenza11 and the risk of death from influenza complications is 6 times higher in this group.12

Chronic conditions that can be exacerbated by influenza

Is influenza B as severe as influenza A?

Yes, in fact influenza B is similar to type A in form i.e. clinical and biological symptoms, and severity16,17 Influenza B is a significant cause of absenteeism, clinic visits, hospitalizations and deaths across all ages18,19,20 It affects and causes mortality in all age groups18. 1 in 3 of hospital admissions with influenza globally were due to influenza B (2014-2015 season).21

Amongst all cases reported with influenza B infection in ICUs, case fatality rates doubled between seasons 2016-17 and 2017-18. The dominant B/Yamagata virus circulation with mixed A virus pattern in 2017/18 caused high severity, long duration of peak influenza activity and all-cause excess mortality in the EU/EEA.22

Severe clinical impact of influenza B during the 2017-18 season in Europe

Economic Burden of Influenza

In the US, influenza accounts for 65% of the annual economic burden of vaccine-preventable diseases1. The total impact of an influenza epidemic in industrialized countries (including direct and indirect costs) may reach €57 million per million people2

    1. PNAS US economic burden
    2. Public health and economic impact of seasonal influenza vaccination with quadrivalent influenza vaccines compared to trivalent influenza vaccines in Europe
    3. The Cost Of US Adult Vaccine Avoidance_ $8.95 Billion In 2015 _ Health Affairs