Flu season
[1] Annually, about 3 to 5 million cases of severe illness and 290,000 to 650,000 deaths from seasonal flu occur worldwide.
Despite the higher incidence of manifestations of the flu during the season, the viruses are actually transmitted throughout populations all year round.
Some proposed explanations are: Research in guinea pigs has shown that the aerosol transmission of the virus is enhanced when the air is cold and dry.
[citation needed] Research done by the National Institute of Child Health and Human Development (NICHD) in 2008 found that the influenza virus has a butter-like coating.
[13] For other southern hemisphere countries such as Argentina, Chile, South Africa, and Paraguay also tend to start around June.
[16] In Hong Kong, which has a humid subtropical climate, the flu season runs from December to March, in the winter and early spring.
Therefore, the World Health Organization (assisted by the National Influenza Centers) recommends two vaccine formulations every year; one for the Northern, and one for the Southern Hemisphere.
Diabetes results in elevated blood sugars in the body, and this environment allows viruses and bacteria to thrive.
[citation needed] If blood sugars are poorly controlled, a mild flu can quickly turn severe, leading to hospitalization and even death.
Uncontrolled blood sugars suppresses the immune systems and generally lead to more severe cases of the common cold or influenza.
[27] Each year flu related complications in the USA affect close to 100,000 asthmatics, and millions more are seen in the emergency room because of severe shortness of breath.
Moreover, many cancer patients undergo radiation therapy and potent immunosuppressive medications, which further suppresses the body's ability to fight off infections.
HIV weakens the body's immune system, leaving them vulnerable to viral, bacterial, fungal, and protozoa disorders.
Many reports have shown that individuals with HIV can develop serious pneumonias that need hospitalization and aggressive antibiotic therapy.
[30] The cost of a flu season in lives lost, medical expenses and economic impact can be severe.
According to the United States Public Health Service, "The epidemic of 1928–1929 was the most important since that of 1920", itself considered to be the final wave, at least in the US, of the 1918 pandemic.
[43] A worldwide epidemic occurred, which for a time was considered to have been a pandemic due to its vast spread, albeit a mild one, with relatively low mortality.
[43] Nevertheless, this experience informed public health experts of the need to update vaccine composition periodically to account for variations in the influenza virus, even if there has been no complete shift in subtype.
[49] After an initial attempt to minimize the threat of the outbreak and a resistance to describe it as an "epidemic",[50][51] the US Public Health Service eventually acknowledged it as such when deaths began to rise around the country.
[49] Around the time that the epidemic was peaking in the US, outbreaks developed in France, Germany, and southern England and later in Scandinavia, Switzerland, and Austria; sporadic activity was reported in other parts of Europe.
This season was particularly severe in England and France, in which pneumonia and influenza excess mortality was two to three times greater than in other countries.
[54] By contrast, North America (the US and Canada) experienced a relatively milder epidemic than other places, with lower all-cause excess mortality and a lower increase in both pneumonia-influenza and all-cause excess mortality, both indicating that this season had a lesser impact in North America relative to other countries.
