H1N1, sometimes known as swine flu, can affect both pigs and humans. Swine flu is a respiratory disease that results from an influenza A virus. It can cause flu-like symptoms, which may become severe in some cases.

The influenza A variant subtype H1N1 is commonly the cause of swine flu in humans. It has similar genetic features to the H1N1 subtype of influenza virus that causes influenza in pigs.

Other main subtypes known to occur and cause influenza in pigs include H1N2 and H3N2Trusted Source. There have been infections in humans with these two variant subtypes as well.

In 2009, the H1N1 variant became widespread in humans for the first time.

Since 2009, the H1N1 virus has become one of the common viruses that circulate each flu season. Many people now have some immunity to the virus. As a result, experts are now less concerned about this type of swine flu than they were in 2009.

However, any time a virus affects humans from a different source, it is a concern. Scientists cannot always tell how a new virus will affect people, or how it will change over time.

a person washing their hands to prevent the spread of swine fluShare on Pinterest
A person can help prevent the spread of swine flu by washing their hands regularly with soap and water.

The symptoms of swine flu are similar to those of regular flu.

They include:

In severe cases, there may be respiratory failure and death, but this is rare. Most people’s symptoms are relatively mild.

However, young children, older people, pregnant women, and those with a compromised immune system may have a higher risk.

Find out more about flu here.

Scientists developed a vaccineTrusted Source to protect humans from H1N1 after the 2009 outbreak. Since then, protection against H1N1 has become part of the regular seasonal flu shot.

Every year, experts try to predict which flu virus strains are likely to circulate during the flu season, which usually peaks in winter. They prepare vaccines according to the types that are most likely to occur.

If experts predict that a certain strain of H1N1 could cause a pandemic, health authorities will recommend including a change to this component in the annual flu shot.

TheTrusted SourceCenters for Disease Control and Prevention (CDC) recommend an annual flu shot for everyone aged 6 months or olderTrusted Source, barring certain rare exceptions. A doctor can advise on individual needs.

Most people recover from H1N1 without extensive medical intervention.

In some cases, however, a doctor may prescribe an antiviral medicationTrusted Source. These drugs can shorten the duration of symptoms and reduce their severity.

People may need these drugs urgently if they:

  • have severe symptoms or complications
  • are in the hospital
  • have a high risk of complications

Steps for managing swine flu symptoms and preventing further infection include:

  • using over-the-counter remedies
  • washing hands regularly with soap and water
  • getting plenty of sleep
  • exercising often
  • managing stress
  • drinking liquids
  • eating a balanced diet
  • avoiding being close to someone with flu symptoms
  • not touching surfaces that may have the virus

Anyone who has flu should stay home from work or school while symptoms last.

Doctors now consider H1N1 to be a flu strain that can occur in people and spread alongside seasonal flu viruses. A person can catch it if they are in close contact with someone who has H1N1.

People who work with swine may have a risk of contracting new types of flu or other diseases from animals. These are known as zoonotic diseasesTrusted Source.

Risk factors

Some people have a higher risk of flu, including H1N1, or having severe symptoms or complications.

These individuals includeTrusted Source:

  • people aged over 65 years
  • children under 5 years
  • people with conditions, such as diabetes, HIV, or cancer
  • pregnant women
  • people with chronic lung disease, such as asthma
  • people with chronic heart disease, such as heart failure
  • anyone with a compromised immune system
  • children with neurologic conditions

If a doctor suspects that a person may have H1N1 or another type of flu, they may recommend a testTrusted Source to confirm the diagnosis.

The rapid influenza diagnostic test can help identify swine flu. However, this test can vary in effectiveness and may show a negative result when a certain influenza virus strain is present.

More accurate tests are available in specialist laboratories.

Most people do not need more than a rapid flu test, as treatment will be the same, regardless of the test outcome.

If a person has flu, the following tips can help prevent further spread:

  • Limit your contact with other people.
  • Do not go to work or school while experiencing flu symptoms.
  • Cover the mouth with a tissue when coughing or sneezing. If no tissue is handy, cover the mouth and nose with your hand or crooked arm.
  • Put your used tissues in a trash can.
  • Wash your hands and face regularly.
  • Keep all surfaces that you touch clean.
  • Follow all doctors’ instructions.

The annual flu shot can offer protection from various types of flu.

Those whose work or lifestyle brings them into contact with swine and other animals shouldTrusted Source:

  • follow all health and safety precautions when handling animals
  • ensure that swine have their relevant vaccinations
  • call a vet if an animal appears sick
  • avoid contact with pigs if they or other animals appear ill

Here are some more facts about swine flu:

Can I catch swine flu from pork?

Swine flu is a respiratory disease that transmits through droplets in the air and on surfaces. It is not possible to catch if from eating properly cooked pork.

Could there be another pandemic?

Another pandemic of H1N1 swine flu is much less likely now, as people have developed some degree of immunity. Before the 2009–2010 pandemic,Trusted Source there was no evidence that H1N1 had infected humans.

Under the right conditions, however, a pandemic can occur if any novel virus moves from animals to humans.

The SARS-CoV-19 virus that causes COVID-19, the infection that first appeared in December 2019, is currently being monitored by the World Health Organization (WHO)Trusted Source.

What does swine flu look like in pigs?

Symptoms in pigs includeTrusted Source:

  • fever
  • depression
  • coughing (barking)
  • runny nose
  • red and runny eyes
  • breathing difficulty
  • low appetite

Swine flu is common in pigs in the United States, but vaccines are available.