Table of ContentsView AllTable of ContentsThe 2009 PandemicDoes It Still Exist?Its SpreadIts ContagiousnessWho Can Get It?When to Seek Medical Care
Table of ContentsView All
View All
Table of Contents
The 2009 Pandemic
Does It Still Exist?
Its Spread
Its Contagiousness
Who Can Get It?
When to Seek Medical Care
The H1N1 virus—known as swine flu—is one type ofinfluenza Avirus. Influenza A(H1N1) viruses still exist today.
Scientists call it the A (H1N1)pdm09 virus. Influenza type A and type B viruses cause disease epidemics in people during flu season. During most years, this is the winter months.
The H1N1 virus emerged during the 2009–2010flu season, when it caused apandemic. It is often called swine flu because it is a combination of influenza viruses that infect pigs, birds, and humans. Today, it is one of the strains that causes seasonal flu.
The H1N1 virus causes common flu symptoms in most people. Those who are pregnant, have a chronic health problem, or have aweakened immune systemhave a higher risk of severe effects from this virus.
This article describes H1N1 virus history, causes, and risks.
Elena Medoks / Getty Images
What Was the Swine Flu Pandemic in 2009?
The swine flu pandemic in 2009 was a global outbreak of the influenza A(H1N1) pdm09 virus. It was a strain of influenza viruses never before identified as a cause of infections in humans. The virus originated from animal influenza viruses that typically attack swine.
The first reports of the swine flu occurred in a 10-year-old patient in California in April 2009. An 8-year-old patient was infected with the same novel virus in an adjacent California county a few days later. The virus spread quickly around the world. The World Health Organization (WHO) declared the H1N1 pandemic in June 2009, affecting people worldwide.
The H1N1 virus that caused the swine flu pandemic in 2009 was very different from other H1N1 viruses existing at the time. Few young people had been able to build up an antibody response to this new virus before being infected. However, people older than age 60 had antibodies to protect them from the virus, likely from exposure to earlier H1N1 viruses earlier in their lives. As a result, the virus primarily affected children and young and middle-aged adults.
An H1N1 vaccine was produced and available in large quantities in late November 2009. However, this was after the peak of illness during the second wave of flu infections had come and gone in the United States.WHO declared an end to the pandemic on August 10, 2010.
Impact of the 2009 Swine Flu PandemicStatistics from the CDC reflect the impact of the swine flu from April 12, 2009, to April 10, 2010, during the H1N1 pandemic in the United States:60.8 million cases274,304 hospitalizations12,469 deathsThe CDC estimated that 151,700 to 575,400 people died from the 2009 H1N1 viral infection during the first year that the virus circulated. The majority of these deaths occurred in Southeast Asia and Africa, where there was likely limited access to disease prevention and treatment.
Impact of the 2009 Swine Flu Pandemic
Statistics from the CDC reflect the impact of the swine flu from April 12, 2009, to April 10, 2010, during the H1N1 pandemic in the United States:60.8 million cases274,304 hospitalizations12,469 deathsThe CDC estimated that 151,700 to 575,400 people died from the 2009 H1N1 viral infection during the first year that the virus circulated. The majority of these deaths occurred in Southeast Asia and Africa, where there was likely limited access to disease prevention and treatment.
Statistics from the CDC reflect the impact of the swine flu from April 12, 2009, to April 10, 2010, during the H1N1 pandemic in the United States:
The CDC estimated that 151,700 to 575,400 people died from the 2009 H1N1 viral infection during the first year that the virus circulated. The majority of these deaths occurred in Southeast Asia and Africa, where there was likely limited access to disease prevention and treatment.
Does the H1N1 Virus Still Exist?
Influenza A(H1N1) viruses still exist today, though it is considered under control. It is related to the H1N1 virus that caused a flu pandemic in 2009-2010.
H1N1 continues to exist as a seasonal flu virus, causing illness, hospitalization, and deaths worldwide. The seasonal flu vaccine has included a component that protects against H1N1 every year since 2010.
How Does H1N1 Spread?
The swine fluincubation period(the amount of time it takes for the infection to develop after you have been exposed to H1N1) is up to seven days. An infected person can likely spread the virus from about a day before developing symptoms until about seven days after symptoms begin. If you have a weakened immune system, you may be able to spread the virus for a slightly longer time.
How Contagious Is H1N1?
H1N1 is now part of the seasonal flu.The spread involves one of the following circumstances:
While the swine flu is related to a virus that affects pigs, you can’t catch swine flu from eating pork.
How Germs Are Transmitted—And How to Protect Yourself
Who Can Get H1N1 Today?
Anyone can get H1N1 today. However, people who have underlying medical conditions and/or compromised immune systems are more likely to get the most severe illness.
The following groups have the highest risk of getting the swine flu and becoming the sickest from it:
Symptoms of the Flu
When to See a Healthcare Provider
If you are in general good health and become infected with H1N1, you may not need to see a healthcare provider. Most people who become infected with swine flu can endure symptoms of H1N1 and recover without complications.
People who are pregnant, immunocompromised, or have a chronic disease, and others who have a high risk of complications from the flu should contact a healthcare provider when flu symptoms develop.
Get immediate medical care if you have swine flu and develop any of the following emergency symptoms:
An emergency in symptoms for children with the flu is slightly different from those that affect adults. Get immediate medical if your child develops any of the following symptoms while they have the flu:
Differences and Similarities Between Influenza A and Influenza B
Summary
The H1N1 virus is a type of influenza A virus. It is also called swine flu because it formed from the virus that affects pigs before it became H1N1 and infected humans.
This virus causes common flu symptoms in most people. Like other types of flu, you have a higher risk of severe symptoms if you have a chronic condition, a weakened immune system, or are pregnant.
While the H1N1 virus still exists today, it is under control. The annual vaccine protects against the H1N1 virus and other strains of the flu most common for the flu season it is given.
11 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Beacon Health System.H1N1 flu (swine flu).Centers for Disease Control and Prevention.The 2009 H1N1 pandemic: summary highlights, April 2009-April 2010.Centers for Disease Control and Prevention.2009 H1N1 pandemic (H1N1pdm09 virus).Centers for Disease Control and Prevention.Tackling the H1N1 flu pandemic through the rapid detection of the novel H1N1 virus.American Academy of Family Physicians.H1N1 influenza.European Centre for Disease Prevention and Control.Questions and answers on the pandemic (H1N1) 2009.Mount Sinai.H1N1 influenza (swine flu).World Health Organization.Influenza A (H1N1): pandemic 2009—2010.Centers for Disease Control and Prevention.About swine/variant flu.New York State Department of Health.H1N1 flu and seasonal flu: differences and similarities.Centers for Disease Control and Prevention.Flu symptoms & complications.
11 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Beacon Health System.H1N1 flu (swine flu).Centers for Disease Control and Prevention.The 2009 H1N1 pandemic: summary highlights, April 2009-April 2010.Centers for Disease Control and Prevention.2009 H1N1 pandemic (H1N1pdm09 virus).Centers for Disease Control and Prevention.Tackling the H1N1 flu pandemic through the rapid detection of the novel H1N1 virus.American Academy of Family Physicians.H1N1 influenza.European Centre for Disease Prevention and Control.Questions and answers on the pandemic (H1N1) 2009.Mount Sinai.H1N1 influenza (swine flu).World Health Organization.Influenza A (H1N1): pandemic 2009—2010.Centers for Disease Control and Prevention.About swine/variant flu.New York State Department of Health.H1N1 flu and seasonal flu: differences and similarities.Centers for Disease Control and Prevention.Flu symptoms & complications.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Beacon Health System.H1N1 flu (swine flu).Centers for Disease Control and Prevention.The 2009 H1N1 pandemic: summary highlights, April 2009-April 2010.Centers for Disease Control and Prevention.2009 H1N1 pandemic (H1N1pdm09 virus).Centers for Disease Control and Prevention.Tackling the H1N1 flu pandemic through the rapid detection of the novel H1N1 virus.American Academy of Family Physicians.H1N1 influenza.European Centre for Disease Prevention and Control.Questions and answers on the pandemic (H1N1) 2009.Mount Sinai.H1N1 influenza (swine flu).World Health Organization.Influenza A (H1N1): pandemic 2009—2010.Centers for Disease Control and Prevention.About swine/variant flu.New York State Department of Health.H1N1 flu and seasonal flu: differences and similarities.Centers for Disease Control and Prevention.Flu symptoms & complications.
Beacon Health System.H1N1 flu (swine flu).
Centers for Disease Control and Prevention.The 2009 H1N1 pandemic: summary highlights, April 2009-April 2010.
Centers for Disease Control and Prevention.2009 H1N1 pandemic (H1N1pdm09 virus).
Centers for Disease Control and Prevention.Tackling the H1N1 flu pandemic through the rapid detection of the novel H1N1 virus.
American Academy of Family Physicians.H1N1 influenza.
European Centre for Disease Prevention and Control.Questions and answers on the pandemic (H1N1) 2009.
Mount Sinai.H1N1 influenza (swine flu).
World Health Organization.Influenza A (H1N1): pandemic 2009—2010.
Centers for Disease Control and Prevention.About swine/variant flu.
New York State Department of Health.H1N1 flu and seasonal flu: differences and similarities.
Centers for Disease Control and Prevention.Flu symptoms & complications.
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