2009 H1N1 Influenza
What is 2009 H1N1 influenza?
The 2009 H1N1 influenza virus (or flu) is a contagious viral respiratory tract infection. 2009 H1N1 flu is characterized by the abrupt onset of symptoms similar to seasonal flu, such as fever, muscle aches, and sore throat.
This virus was originally referred to as swine flu, because many of its genes resemble a virus that normally occurs in pigs. Additional research has shown, however, that 2009 H1N1 flu is made up of swine flu genes as well as avian and human flu genes.
The World Health Organization (WHO) declared 2009 H1N1 flu a global pandemic in June 2009. As of September 20, 2009, the WHO estimated that 2009 H1N1 is widespread in the U.S., Canada, Mexico, parts of South America, Ireland, New Zealand, Thailand, Australia, and Cambodia. The virus also has spread regionally throughout Brazil, India, and Indonesia, and locally throughout Europe.
Although the virus has spread globally, most individuals in the U.S. who have contracted the virus have fully recovered without medical treatment.
Facts about 2009 H1N1 influenza:
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Unlike seasonal influenza, 2009 H1N1 infections have occurred mainly in younger people. Research suggests that older adults may have some degree of resistance to the virus, potentially due to previous exposure to a related influenza A H1N1 virus that circulated before 1957.
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Like seasonal flu, 2009 H1N1 flu can range from mild to severe, and can be deadly in some cases. Those with chronic medical conditions are at higher risk for complications and death from H1N1. Researchers believe that some people at high risk for seasonal flu complications are also at higher risk for complications from 2009 H1N1 flu.
What causes 2009 H1N1 influenza?
As with seasonal flu, 2009 H1N1 flu is generally passed from person to person by airborne transmission (for example, sneezing or coughing). But, the virus can also live for a short time on objects--such as doorknobs, pens, pencils, keyboards, telephone receivers, and eating or drinking utensils. Therefore, it may also be spread by touching something that has been handled by someone infected with the virus and then touching your own mouth, nose, or eyes.
People who have 2009 H1N1 flu are considered contagious starting one day before they show symptoms and for up to seven or more days after the illness starts. Children and individuals with weakened a immune system may be contagious for an even longer period of time. 2009 H1N1 flu is not spread through food. Eating well-cooked pork and pork products does not pose any risk for infection from this virus.
What are the symptoms of 2009 H1N1 influenza?
2009 H1N1 flu symptoms are similar to the most common symptoms of the seasonal flu. However, each individual may experience symptoms differently. Influenza is called a respiratory disease, but the whole body seems to suffer when a person is infected. People who contract 2009 H1N1 flu usually become acutely ill with several, or all, of the following symptoms:
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Fever
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Headache
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Runny or stuffy nose
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Cough
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Aches and pains
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Fatigue
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Sore throat
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Chills
Some people may also experience diarrhea and vomiting. Children do not always display these symptoms, and may experience difficulty breathing and be less active than normal.
If you experience one or more of the following symptoms, seek emergency medical care immediately:
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Difficulty breathing
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Pressure or pain in the stomach or chest
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Persistent or severe vomiting
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Confusion
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Dizziness
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Flu symptoms that improve and later return with fever and worse cough
Treatment for 2009 H1N1 influenza:
Specific treatment for influenza can vary, and will be determined by your physician based on:
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Your age, overall health, and medical history
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Extent of the virus
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Severity of symptoms
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Tolerance for specific medications
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Expectations for the course of the disease
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Your opinion or preference
The goal of treatment for 2009 H1N1 influenza is to help prevent or decrease the severity of symptoms. Talk with your doctor about what actions are best for you to take.
At this time, the Centers for Disease Control and Prevention (CDC) recommends the antiviral drugs oseltamivir (brand name Tamiflu) or zanamivir (brand name Relenza) to treat people who are hospitalized for 2009 H1N1 or seasonal flu, those who also have more severe symptoms such as a lower respiratory tract infection, or people who are at high risk for complications.
How to prevent 2009 H1N1 influenza:
There are everyday precautions you can take to protect you from getting 2009 H1N1 flu. Following these measures may be helpful:
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Wash your hands with soap and water, especially after you cough or sneeze. Use an alcohol-based hand sanitizer if soap and water are not available.
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Avoid touching your eyes, nose, or mouth.
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Keep surfaces clean by wiping them down with a household disinfectant.
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Maintain a safe distance from people who are sick.
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Cough or sneeze into a tissue, your elbow, or your upper arm.
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Do not share cups or utensils.
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If you become sick, stay home until your fever has been gone for at least 24 hours.
Some people may choose to wear a face mask in crowded settings, though their ability to control the spread of 2009 H1N1 flu is not known at this time.
What types of 2009 H1N1 influenza vaccines are available?
Two forms of vaccine are available to prevent 2009 H1N1 influenza: a nasal spray, known as live, attenuated intranasal vaccine (LAIV), and a shot known as an inactivated vaccine or "flu shot." The 2009 H1N1 LAIV contains live, weakened viruses, while the 2009 H1N1 flu shot contains killed viruses. Both forms of the vaccine are produced by the manufacturers who make seasonal flu vaccines, and they are made in the same way as seasonal flu vaccines.
When and where are 2009 H1N1 influenza vaccines available?
The U.S. Food and Drug Administration has approved several 2009 H1N1 vaccines, and they are currently offered in some states for certain people. Ask your doctor if the 2009 H1N1 flu vaccines are available in your area. If they are, your doctor can tell you if you should receive the vaccine based on your age and existing health conditions.
Children who are age 9 and under should receive two doses of a vaccine, about a month between each dose. All other individuals approved for vaccination should only receive one dose.
Vaccines are beginning to be available in pharmacies, workplaces, and vaccination clinics set up by local schools, health departments, and health care provider offices. Every state has its own plan of action for administering vaccines.
What are the side effects of the 2009 H1N1 flu vaccines?
The CDC expects any side effects to be rare but similar to those seen after receiving a typical flu shot. Side effects of the 2009 H1N1 flu shot may include:
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Fever
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Headache
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Muscle aches
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Redness, soreness, or swelling at the injection site
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Nausea
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Fainting (although this mainly occurs in adolescents)
These symptoms will usually occur soon after receiving the shot, and should last for only a couple of days.
Side effects of the 2009 H1N1 LAIV should be similar to side effects seen with seasonal flu LAIV. These include:
If a person has a severe, life-threatening allergic reaction to the flu shot or nasal spray, seek medical attention immediately. Symptoms will appear very soon after the vaccine has been administered and may include:
Who should be immunized against 2009 H1N1 influenza?
The CDC recommends that these high-risk groups receive the 2009 H1N1 flu shot in addition to the regular flu shot:
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Pregnant women
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Health care workers
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People 6 months to 24 years old
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People 25 to 64 years old with health conditions that put them at higher risk for flu complications
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Caretakers of and people who live with children younger than 6 months
Because infants have a higher risk for flu complications and the vaccine is not approved for those younger than 6 months, experts believe that vaccinating people who have close contact with them can help protect infants from getting 2009 H1N1 flu.
2009 H1N1 LAIV can only be administered to certain individuals depending upon their age and existing health conditions.
According to the CDC, certain individuals should not receive the 2009 H1N1 LAIV:
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People with long-term health problems
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People with a weakened immune system
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People in close contact with someone who has a severely compromised immune system
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Children younger than age 2
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Children who are younger than age 5 and either have asthma or have had wheezing problems over the past year
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Children and adolescents on long-term aspirin treatment
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Anyone with nerve and muscle disorders that may lead to breathing and swallowing problems
If you have any of the following health conditions, consult your doctor before receiving either vaccine:
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You are moderately to severely ill
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You have a severe allergy to eggs or any other substance contained in the vaccine
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You have Guillain-Barre syndrome
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You had a life-threatening reaction after receiving a seasonal flu vaccine
People older than age 65 should receive the flu shot as supplies become available. The CDC recommends that people who were vaccinated for the 1976 swine flu virus should also receive the 2009 H1N1 vaccine.
Traveling and exposure to H1N1 flu:
Because the 2009 H1N1 flu can spread by droplets produced by an infected person who is coughing or sneezing, travelers are very susceptible to contracting this virus.
The CDC recommends that people intending to travel stay home if they are not feeling well. Those who feel ill upon returning from traveling should contact their health care provider.
To avoid potential exposure to H1N1 flu, the CDC advises remaining informed about school closings and avoiding crowds and certain social situations.