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Q&A: H1N1 Influenza

Reviewed by: Mary L. Gavin, MD

What Is H1N1 Influenza?

H1N1 influenza (sometimes still referred to as "swine flu") is a contagious respiratory virus that surfaced in spring 2009. It contains a combination of different flu viruses that affect humans, pigs, and birds. Because of the human component of the virus, this strain can spread from person-to-person more easily than other viruses.

Why Isn't the Virus Called "Swine Flu" Anymore?

Researchers first called this new virus "swine flu" because laboratory tests showed that many of the genes in the virus were similar to flu viruses that North American pigs get. Now, after further research, scientists have determined that the virus is not at all similar to viruses that North American pigs develop. Instead, it's found to have genes from pigs in Europe and Asia, as well as genes from avian (bird) flu and other human flu.

How Does the H1N1 Flu Spread?

H1N1 spreads in the same way that other viruses do — through the air when a person who has the virus sneezes, coughs, or speaks. People also can become infected after touching a contaminated surface or object that someone with the virus touched, sneezed, or coughed on.

As with other flu viruses, people can be contagious a day or so before their symptoms start and remain that way for up to 7 days after getting sick. Very young children and people with immune systems that are weakened due to chronic illness might be contagious for longer.

You can't get the H1N1 flu from eating pork or pork products. Eating properly cooked pork is safe.

Who Is Especially at Risk?

As with other types of flu, children younger than age 5 are at risk for more serious complications from the virus. Also, people older than 65 and anyone with a chronic medical condition (like diabetes, heart disease, asthma or other lung problems, or neurodevelopmental conditions) can have more problems coping with the illness. They might get sicker and need more medical support; in some cases, hospitalization may be necessary.

Pregnant women who catch the flu also are more likely to get sicker. Having the flu can increase the risk for complications during pregnancy, labor, and delivery.

If you're pregnant and have flu-like symptoms or your child is in an at-risk group and develops symptoms, call a doctor right away. The earlier treatment is administered, the lower the chance of serious complications from the flu.

What Are the Symptoms of H1N1 Flu?

H1N1 flu can last anywhere from 7 to 14 days. Symptoms are similar to those of the common flu and include fever plus one or more of the following: cough, sore throat, body aches, headache, chills, fatigue, diarrhea, or vomiting. The virus also can cause pneumonia, which can make it hard to breathe.

Kids who develop any of these symptoms need immediate medical attention:

  • fast breathing or trouble breathing
  • bluish skin color
  • not drinking enough fluids
  • very sleepy or lethargic
  • in babies, being so irritable they don't want to be held
  • fever with a rash
  • flu-like symptoms improve, then return with fever and a worse cough

Is There a Treatment for H1N1 Flu?

Yes. Antiviral medicines used to treat common seasonal flu can ease symptoms and shorten the duration of the illness. These medicines should be reserved for people with severe illness requiring hospitalization or who are at higher risk for developing complications (like pregnant women, people with chronic health conditions, and kids under 5 years old).

In some cases, at-risk people who have been in close contact with someone with H1N1 infection may be given antiviral medication as a precaution against getting the flu (or against getting a severe case of it).

Treat kids with flu at home by making sure that they:

  • drink lots of fluids to prevent dehydration
  • get plenty of sleep and take it easy
  • take acetaminophen or ibuprofen to relieve fever and aches (but do not give aspirin because of risk of Reye syndrome)
  • wear layers, since the flu often makes them cold one minute and hot the next

Remember to call a doctor if your child seems to get better but then feels worse, develops a high fever, has any trouble breathing, or seems confused.

Is There a Vaccine to Protect Against H1N1?

Yes. The 2010-2011 seasonal flu vaccine protects against H1N1 flu. During the 2009-2010 flu season, the seasonal flu shot did not protect against H1N1 flu, so a separate H1N1 flu shot was needed.

The Centers for Disease Control and Prevention (CDC) recommends the flu vaccine for all people age 6 months and older. Certain people are at higher risk of complications from the flu, including:

  • pregnant women
  • children younger than age 5, especially those younger than 2 
  • people age 65 and older
  • people of any age who have chronic health conditions

Infants younger than 6 months are too young to receive the vaccine, but all other high-risk persons should be vaccinated. Health care workers, caregivers, and close contacts of at-risk persons (including those who care for infants younger than 6 months) also should get the flu vaccine.

The vaccine is available as a shot (injected through the skin) or as a spray mist (into the nasal cavity). Kids younger than age 9 need two doses of the vaccine if they have never had a flu shot or did not get the H1N1 vaccine during the 2009-2010 flu season. Older kids and teens only need one dose.

How Else Can I Protect My Family?

Vaccinating your family against the H1N1 flu isn't the only preventive step you can take. The CDC recommends these precautions:

  • Cover your nose and mouth with a tissue when you sneeze or cough and put used tissues in the trash.
  • If you don't have a tissue, cough or sneeze into your upper sleeve, not your hands.
  • Clean your hands after coughing or sneezing — wash with soap and water or use alcohol-based hand cleaner.
  • Avoid touching your eyes, nose, and mouth.
  • Keep sick kids home from childcare or school and limit their contact with others; kids should stay home for at least 24 hours after a fever (of 100º F or 37.8º C or higher) goes away on its own without the use of fever-reducing medicines.
  • If you live in a home with someone who has the flu, be extra cautious about avoiding germs. Don't get in close, face-to-face contact, and clean your hands often.

Breastfeeding mothers who have the flu can continue breastfeeding, even if they're on antiviral medicines. But they might have to take additional precautions (like wearing a facemask) to reduce the risk to their baby. Talk to your doctor about how you can help keep your baby healthy.

Can We Still Eat Pork?

Because the flu virus isn't transmitted through food, the CDC and U.S. Department of Agriculture (USDA) say it's safe to eat pork. Of course, pork should be well cooked to avoid any illness. Cook pork to an internal temperature of 160° F or higher (use a meat thermometer to check the temperature). Don't eat pork that looks pinkish or bloody inside.

There's no evidence that touching raw pork will transmit the virus, but it's always wise to wash your hands and all surfaces after touching any raw meat.

Can North American Pigs Get the Virus?

Outbreaks of the H1N1 flu have been reported in pigs in the U.S. and Canada. Health officials are working on a vaccine for pigs that would protect against H1N1 flu as a way of preventing further spread of the disease to humans.

Reviewed by: Mary L. Gavin, MD
Date reviewed: August 2010