page_title: 2009 swine flu pandemic
section_title: History
hierarchical_section_title: 2009 swine flu pandemic / History
caption_attribution_description: Mexican military giving out swine flu masks. They are the #1 fashion accessory around here right now.
context_page_description: The 2009 swine flu pandemic was an influenza pandemic that lasted for about 19 months, from January 2009 to August 2010, and was the second of two pandemics involving H1N1 influenza virus. First described in April 2009, the virus appeared to be a new strain of H1N1, which resulted from a previous triple reassortment of bird, swine, and human flu viruses further combined with a Eurasian pig flu virus, leading to the term "swine flu".
  Some studies estimated that the actual number of cases including asymptomatic and mild cases could be 700 million to 1.4 billion people—or 11 to 21 percent of the global population of 6.8 billion at the time. The lower value of 700 million is more than the 500 million people estimated to have been infected by the Spanish flu pandemic.
  The number of lab-confirmed deaths reported to the WHO is 18,449, though this 2009 H1N1 flu pandemic is estimated to have actually caused about 284,000 deaths. A follow-up study done in September 2010 showed that the risk of serious illness resulting from the 2009 H1N1 flu was no higher than that of the yearly seasonal flu. For comparison, the WHO estimates that 250,000 to 500,000 people die of seasonal flu annually.
context_section_description: Analysis of the genetic divergence of the virus in samples from different cases indicated that the virus jumped to humans in 2008, probably after June, and not later than the end of November, likely around September 2008. The research also indicated the virus had been latent in pigs for several months prior to the outbreak, suggesting a need to increase agricultural surveillance to prevent future outbreaks. In 2009, U.S. agricultural officials speculated, although emphasizing that there was no way to prove their hypothesis, that "contrary to the popular assumption that the new swine flu pandemic arose on factory farms in Mexico, [the virus] most likely emerged in pigs in Asia, but then traveled to North America in a human." However, a subsequent report by researchers at the Mount Sinai School of Medicine in 2016 found that the 2009 H1N1 virus likely originated from pigs in a very small region of central Mexico.
  Initially called an "outbreak", widespread H1N1 infection was first recognized in the state of Veracruz, Mexico, with evidence that the virus had been present for months before it was officially called an "epidemic". The Mexican government closed most of Mexico City's public and private facilities in an attempt to contain the spread of the virus; however, it continued to spread globally, and clinics in some areas were overwhelmed by infected people. The new virus was first isolated in late April by American and Canadian laboratories from samples taken from people with flu in Mexico, Southern California, and Texas. Soon the earliest known human case was traced to a case from 9 March 2009 in a 5-year-old boy in La Gloria, Mexico, a rural town in Veracruz. In late April, the World Health Organization (WHO) declared its first ever "public health emergency of international concern," or PHEIC, and in June, the WHO and the U.S. CDC stopped counting cases and declared the outbreak a pandemic.
  Despite being informally called "swine flu", the H1N1 flu virus cannot be spread by eating pork products; similar to other influenza viruses, it is typically contracted by person to person transmission through respiratory droplets. Symptoms usually last 4–6 days. Antivirals (oseltamivir or zanamivir) were recommended for those with more severe symptoms or those in an at-risk group.
  The pandemic began to taper off in November 2009, and by May 2010, the number of cases was in steep decline. On 10 August 2010, the Director-General of the WHO, Margaret Chan, announced the end of the H1N1 pandemic and announced that the H1N1 influenza event had moved into the post-pandemic period. According to WHO statistics (as of July 2010), the virus had killed more than 18,000 people since it appeared in April 2009; however, they state that the total mortality (including deaths unconfirmed or unreported) from the H1N1 strain is "unquestionably higher". Critics claimed the WHO had exaggerated the danger, spreading "fear and confusion" rather than "immediate information". The WHO began an investigation to determine whether it had "frightened people unnecessarily". A flu follow-up study done in September 2010, found that "the risk of most serious complications was not elevated in adults or children." In a 5 August 2011 PLOS ONE article, researchers estimated that the 2009 H1N1 global infection rate was 11% to 21%, lower than what was previously expected. However, by 2012, research showed that as many as 579,000 people could have been killed by the disease, as only those fatalities confirmed by laboratory testing were included in the original number, and meant that many without access to health facilities went uncounted. The majority of these deaths occurred in Africa and Southeast Asia. Experts, including the WHO, have agreed that an estimated 284,500 people were killed by the disease, much higher than the initial death toll.
caption: Mexican soldiers distributing protective masks to citizens
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