2009 H1N1 Flu Pandemic Timeline
A timeline of major events that took place during the 2009 H1N1 flu pandemic.
www.cdc.gov
April 15
First human infection with new influenza A H1N1 virus detected in California.
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.
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H1N1 lab test
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 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.
June 25
CDC estimated at least 1 million cases of 2009 H1N1 influenza had occurred in the United States.
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Early July
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.
July 22
Clinical trials testing the 2009 H1N1 flu vaccine began.
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.
swine flu action center
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
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October 5
First doses of H1N1 vaccine were given in the U.S.