Influenza is a viral respiratory disease of global importance; indeed, many experts believe that an influenza pandemic is the greatest threat to global public health. In 2018, the world observed the centenary of the start of the 1918–1919 influenza pandemic. Its estimated toll of up to 50 million deaths exceeded that of the First World War, resulting in a dramatic decline in life expectancy in many countries at the time of the pandemic. Its impact led to fundamental changes in public health and health care systems, including centralized and consolidated health care, greater recognition of the role of socioeconomics in health, and the coordination of public health at national and global levels.
Pandemic (H1N1) 2009 caused significant deaths, particularly in those aged under 65 years; it also tested national health response systems (in particular, the pandemic vaccine response capacity) and exposed weaknesses in those systems. It reiterated that influenza viruses of both avian and swine origin can cause a pandemic, and it underscored the importance of intersectoral collaboration for pandemic preparedness. Although it is impossible to predict when the next pandemic might occur, its occurrence is considered inevitable, and it could well occur during the time frame of this strategy. Given increased economic globalization, urbanization and mobility, the next pandemic will spread further and faster, and could lead to significant disruptions. Despite significant medical advances over the past 100 years, there will still be populations that have limited access to care and will be likely to experience high mortality rates during a pandemic.
The substantial morbidity and mortality due to influenza – well-recognized during a pandemic – is often underappreciated in the context of year-round seasonal influenza. Seasonal influenza viruses evolve continuously and cause severe disease annually, particularly in the elderly, children, pregnant women and people with underlying chronic conditions. Each year, across the globe, there are an estimated 1 billion cases of influenza, of which 3–5 million are severe cases and 290 000–650 000 lead to influenza-related respiratory deaths. Outbreaks of influenza highlight the burden and severity of annual epidemics on the global population and countries’ health systems, as evidenced by seasonal epidemics that have significantly affected low- and middle-income countries (LMICs). Seasonal epidemics also highlight the economic burden due to direct medical costs and indirect costs, such as loss of productivity due to work absenteeism.
Building on its 70 years of global health leadership and six critical functions, the WHO developed the Global Influenza Strategy for 2019–2030 to enhance global and national pandemic preparedness, to combat the ongoing threat of zoonotic influenza, and to improve seasonal influenza prevention and control in all countries. The strategy presents a unifying vision, and global goals and priorities that will rely on commitments from WHO, countries and partners for full implementation.