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H1N1 Flu Pandemic 2009 |
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The 2009 (H1N1)pdm09 Pandemic: A New Flu Virus EmergesApril, 2009: The (H1N1)pdm09 virus was very different from H1N1 viruses that were circulating at the time of the pandemic. Few young people had any existing immunity (as detected by antibody response) to the (H1N1)pdm09 virus, but nearly one-third of people over 60 years old had antibodies against this virus, likely from exposure to an older H1N1 virus earlier in their lives. Vaccination with seasonal flu vaccines offered little cross-protection against (H1N1)pdm09 virus infection. While a vaccine was not available until late November—after the peak of illness during the second wave had come and gone in the United States. From April 12, 2009 to April 10, 2010, CDC estimated that in the United States - there were 60.8 million cases , 274,304 hospitalizations , and 12,469 deaths Additionally, 151,700-575,400 people worldwide died during the first year .** Globally, 80% of virus-related deaths occurred in people younger than 65 years of age. This differs greatly from typical seasonal influenza epidemics, during which about 70% to 90% of deaths are estimated to occur in people 65 years and older. Though the 2009 flu pandemic primarily affected children and young and middle-aged adults, the impact of the (H1N1)pdm09 virus on the global population during the first year was less severe than that of previous pandemics. Estimates of pandemic influenza mortality ranged from 0.03 percent of the world’s population during the 1968 H3N2 pandemic to 1 percent to 3 percent of the world’s population during the 1918 H1N1 pandemic. It is estimated that 0.001% to 0.007% of the world’s population died of respiratory complications associated with (H1N1)pdm09 virus during the first 12 months. The United States mounted a complex, multi-faceted and long-term response to the pandemic, summarized in The 2009 H1N1 Pandemic: Summary Highlights, April 2009-April 2010. On August 10, 2010, WHO declared an end to the global 2009 H1N1 influenza pandemic. However, (H1N1)pdm09 virus continues to circulate as a seasonal flu virus, and cause illness, hospitalization, and deaths worldwide every year. In the US from 2009 - 2018, influenza A H1N1pdm09 has caused at least: 100.5 million illnesses, 936,000 hospitalizations, 75,000 deaths Compared to ALL FLUs 2010-2019 in the US around 4 million hospitalizations, 340,000 deaths COVID-19 the 7th Human Coronavirus
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| April 17 | Second human infection with the new influenza A H1N1 virus detected in California about 130 miles away from first infection, with no known connection to previous patient. |
| April 18 | First novel 2009 H1N1 flu infections were reported by CDC to the World Health Organization (WHO) through the U.S. International Health Regulations Program. |
| April 21 | CDC publicly reported the first two U.S. infections with the new H1N1 virus. CDC began working to develop a candidate vaccine virus. |
| April 22 | CDC activated it’s Emergency Operations Center (EOC). |
| April 23 | Two additional human infections with 2009 H1N1 were detected in Texas, transforming the investigation into a multistate outbreak and response. |
| April 24 | CDC uploaded complete gene sequences of new H1N1 2009 virus to a publically-accessible international influenza database. |
| April 25 | The World Health Organization (WHO) declared a public health emergency of international concern. |
| April 26 | The United States Government declared 2009 H1N1 a Public Health Emergency of International Concern and CDC began releasing 25% of antiviral drugs needed to treat this new influenza virus from the federal stockpile. |
| April 27 | WHO Director-General raised the level of influenza pandemic alert from phase 3 to phase 4, based on data showing person-to-person spread and the ability of the virus to cause community-level outbreaks. |
| April 28 | The Food and Drug Administration (FDA) approved a new CDC test to detect 2009 H1N1 infections CDC issued the first CDC Interim Guidance on Closing Schools and Childcare Facilities, recommending a 7-day dismissal in affected schools and childcare facilities with laboratory-confirmed cases of influenza A H1N1 virus. |
| April 29 | WHO raised the level of influenza pandemic alert from phase 4 to phase 5, signaling that a pandemic was imminent, and requested all countries to immediately activate their pandemic preparedness plans and be on high alert for unusual outbreaks of influenza-like illness and severe pneumonia. |
| May 2009 | H1N1 influenza summer activity peaked in the United States during May and June. |
| May 1 | Domestic and global shipments of new CDC test to detect 2009 H1N1 began. CDC updated the CDC Interim Guidance on Closing Schools and Childcare Facilities, recommending affected communities with lab-confirmed cases of influenza A H1N1 consider adopting school dismissal and childcare closing measures, including closing for up to 14 days depending on the extent and severity of influenza illness. |
| May 4 | CDC shifted from reporting confirmed cases of 2009 H1N1 to reporting both confirmed and probable cases of 2009 H1N1. |
| May 5 | Peak school dismissal day in the spring phase of the pandemic. 980 schools were dismissed, affecting 607,778 students. |
| May 6 | CDC distributed updated recommendations for the use of influenza antiviral medicines to provide guidance for clinicians in prescribing antiviral medicines for treatment and prevention (chemoprophylaxis) of 2009 H1N1 influenza. |
| May 8 | CDC issued an MMWR updating the 2009 H1N1 influenza situations in Mexico, the United States, and worldwide. |
| May 12 | CDC reported early data on 2009 H1N1 illness among pregnant women in an MMWR. |
| June 11 | The World Health Organization (WHO) declared a pandemic and raised the worldwide pandemic alert level to phase 6, which means the virus was spreading to other parts of the world. CDC held its first press conference with former CDC Director Thomas Frieden, MD, MPH. The press conference had 2,355 participants. |
| June 25 | CDC estimated at least 1 million cases of 2009 H1N1 influenza had occurred in the United States. |
| June 19 | All 50 states, the District of Colombia, Puerto Rico and the U.S. Virgin Islands had reported cases of 2009 H1N1 infection. By late-June, more than 30 summer camps in the U.S. had reported outbreaks of 2009 H1N1 influenza illness. CDC released guidance for day and residential camps to reduce spread of influenza. July (Early) Reported cases of 2009 H1N1 nearly doubled since mid-June 2009. Three 2009 H1N1 influenza viruses that were resistant to the antiviral drug, oseltamivir, were detected in three countries. |
| July 10 | CDC reported findings in an MMWR that indicated a large prevalence of obesity in intensive care patients with confirmed 2009 H1N1 influenza infection. After mid-July, 2009 H1N1 influenza activity declined in most countries. |
| August | Additional oseltamivir-resistant 2009 H1N1 viruses were detected by CDC. |
| August 3 | CDC School Dismissal Monitoring System (SDMS) activated. |
| August 19 | CDC Guidance for Businesses and accompanying toolkit posted to CDC.gov. |
| August 20 | CDC Guidance for Institutions of Higher Education (IHE) and accompanying toolkit posted to CDC.gov. Calls were conducted with Secretary Duncan and Sebelius to explain guidance. Press briefings followed. Second wave of 2009 H1N1 influenza activity began in the U.S. |
| August 30 | New reporting season for the 2009-2010 influenza season began. |
| September 1 | More than 1,000 test kits shipped to 120 domestic and 250 international laboratories in 140 countries since May 1, 2009. |
| September 3 | CDC published a study that analyzed
data related to H1N1 influenza pediatric
deaths reported to CDC from April to August 2009 in MMWR. Data showed 477 deaths with lab-confirmed 2009 H1N1 flu in the U.S. had been reported to CDC as of August 8, 2009. |
| September 10 | HHS secretary and CDC Director joined the National Foundation for Infectious Diseases (NFID) in a news conference to stress the importance of getting vaccinated for the upcoming influenza season. |
| September 15 | The FDA announced its approval of four 2009 H1N1 influenza vaccines. |
| September 30 | U.S. states placed first orders of 2009 H1N1 vaccine. |
| October | National Influenza 2009 H1N1 vaccination campaign |
| October 5 | First doses of H1N1 vaccine were given in the U.S. |
| October 24 | Influenza activity reached its highest level in the reporting week ending October 24, 2009, with 48 of 50 states reported widespread activity. October, Late Second wave of H1N1 flu activity peaked in the U.S. |
| November 12 | CDC released its first estimates official estimates of 2009 H1N1 cases, hospitalization and deaths. |
| November 16 | FDA announced its approval of a fifth 2009 H1N1 vaccine. |
| November 23 | No school closures throughout United States; first time since 8/25/2009. December Results of trials conducted among adults were published in December, and the data indicated that the immune response among vaccinated adults was excellent. |
| December 4 | CDC published preliminary safety
results for the 2009 H1N1 vaccines for the first months of reports received
through the U.S. Vaccine Adverse Event Reporting System . |
| December 18 | First 100 million doses of 2009 H1N1 vaccine were available for ordering. December, late 2009 H1N1 vaccination had been opened up to anyone who wanted it. |
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