H1N1: 2009 flu pandemic

The 2009 flu pandemic is a global outbreak of a new strain of a influenza A virus subtype H1N1, officially named the "new H1N1", first identified in April 2009, and commonly called "Swine flu." It is thought to be a reassortment of four known strains of influenza A virus: one endemic in (normally infecting) humans, one endemic in birds, and two endemic in pigs (swine). Transmission of the new strain is human-to-human, with cooked pork products safe to eat as the virus cannot be transmitted by eating foods. The outbreak began in Mexico, with evidence that Mexico was already in the midst of an epidemic for months before the outbreak was recognized. Soon after, its government closed down most of Mexico City's public and private offices and facilities to help contain the spread. In early June, as the virus spread globally, the World Health Organization (WHO) declared the outbreak to be a pandemic, but also noted that most illnesses were of "moderate severity." The virus has since spread to the Southern Hemisphere which entered its winter flu season, and to many less developed countries with limited healthcare systems. Because the virus was spreading with "unprecedented speed", and many clinics were overwhelmed testing and treating patients, WHO stopped requiring countries to report all cases, but is still monitoring unusually large outbreaks. The virus typically spreads from coughs and sneezes or by touching contaminated surfaces and then touching the nose or mouth. Symptoms, which can last up to a week, are similar to those of seasonal flu, and may include fever, sneezes, sore throat, coughs, headache, and muscle or joint pains. The U.S. Centers for Disease Control and Prevention (CDC) notes that most cases worldwide have been mild so far and most hospitalizations and deaths have been of persons that also had underlying conditions such as asthma, diabetes, obesity, heart disease, or a weakened immune system. Then again, Dr Anne Schuchat from CDC thinks, "this is a virus that's capable of causing a spectrum of illness that includes severe complications and death". "It's very important we take this virus seriously".As the virus spreads easily between people, through the air or surface contact, those who get the flu are recommended to stay home from school or work and avoid crowds to avoid spreading the infection further. In an attempt to slow the spread of the illness, a number of countries, especially in Asia, have quarantined airline passengers with flu symptoms, while some are also pre-screening passengers. WHO does not expect to have a full vaccine before the end of 2009, and vaccines available sooner may be limited and given first to healthcare workers, pregnant women, and other higher risk groups. Two or three injections will be required for maximum immunity from both the swine flu and seasonal flu. There is also concern if the new virus mutates further, it could become more virulent and less susceptible to any new vaccine. Historical context: Annual influenza epidemics are estimated to affect 5–15% of the global population. Although most cases are mild, this still causes severe illness in 3–5 million people and around 250,000–500,000 deaths worldwide. In industrialized countries severe illness and deaths occur mainly in the high-risk populations of infants, the elderly, and chronically ill patients. In addition to these annual epidemics, Influenza A virus strains caused three major global epidemics during the 20th century: the Spanish flu in 1918, Asian flu in 1957 and Hong Kong flu in 1968–69. These pandemics were caused by strains of Influenza A virus that had undergone major genetic changes and for which the population did not possess significant immunity.The influenza virus has also caused several pandemic threats over the past century, including the pseudo-pandemic of 1947, the 1976 swine flu outbreak and the 1977 Russian flu, all caused by the H1N1 subtype. The world has been at an increased level of alert