Pandemic (H1N1) Influenza Vaccine

As of the August 2010, pandemic H1N1 flu is no longer considered a pandemic. This fact sheet provides historical information about pandemic H1N1 flu and will no longer be updated. Please see the Centers for Disease Control and Prevention website at http://www.cdc.gov/h1n1flu/ for the latest information about H1N1 flu.

What Is Pandemic (H1N1) Influenza?

Pandemic H1N1 flu (originally called swine flu ) is a respiratory infection. The pandemic H1N1 flu has spread to humans and has reached the level of a pandemic. A pandemic is a worldwide outbreak.

The main risk factor for getting the pandemic H1N1 flu is contact with an infected person. People with the flu can infect others through coughing and sneezing. You can also get the flu by touching an infected object. A chronic health condition such as heart or lung disease, diabetes, or cancer may increase your risk of a more severe form of the flu.

Symptoms may include:

Fever and chills
Sore throat
Cough
Severe muscle aches
Severe fatigue
Headache
Runny nose, nasal congestion
Sneezing
Watery eyes
Stomach symptoms like nausea, vomiting, and diarrhea

Most people recover at home. Basic care includes rest, fluids, and over-the-counter pain relievers. Antiviral medicines such as zanamivir (Relenza) and oseltamivir (Tamiflu) may be used. They may be given to prevent or treat an H1N1 infection.

What Is the H1N1 Flu Vaccine?

A vaccine is a substance used to protect people from infections caused by bacteria and viruses. There are two ways you might receive the H1N1 flu vaccine:

Shot given in the muscle—uses inactivated vaccine containing dead virus
Nasal spray—uses live, attenuated vaccine containing weakened virus

The virus in a vaccine will not make you sick. Be aware that even if you have been vaccinated, you can still get the pandemic H1N1 flu. If you have symptoms, tell your doctor.

Is the H1N1 Flu Vaccine Available?

Yes, the H1N1 flu vaccine is available. The supply varies by location.

Who Should Get Vaccinated and When?

According to the CDC, those who should get vaccinated include:

Pregnant women
Anyone who lives with or cares for a child under the age of six months
Healthcare workers and emergency medical personnel
People aged six months to 24 years
People aged 25-64 years with chronic medical conditions (eg, asthma ) or compromised immune systems

The Public Health Agency of Canada has similar target groups to the CDC but also include:

People living in remote areas
People handling pigs or poultry

People in these target groups who have had flu-like illness not confirmed to be pandemic H1N1 flu should still be vaccinated.

Pregnant women should be given the flu shot (the inactivated vaccine), not the nasal spray (live, attenuated vaccine).

Should there be a shortage of vaccine, the target populations would consist of:

Pregnant women
Anyone who lives with or cares for a child under the age of six months
Healthcare workers and emergency medical personnel
People aged six months to four years
Children aged 5-18 years with chronic medical conditions

After the target groups, people aged 25-64 years should get the vaccine. Older adults (over 65 years) will be the last group to receive the vaccine. (Older adults have been less likely to become infected with this flu than younger people.)

The nasal spray will be given in two doses one month apart for children aged 2-9 years. Some doctors say it is fine to give the doses two weeks apart, instead of one month apart. Talk to your child's doctor about what is best for your child. People aged 10-49 years will only need one dose of the nasal spray vaccine.

The shot will be given in two doses one month apart to children aged six months to nine years. Some doctors say it is fine to give the doses three weeks apart, instead of one month apart. Talk to your child's doctor about what is best for your child. People aged 10 years and older will only need one dose.

Flu season can begin as early as October and last as late as April or May. The best time to get vaccinated is as soon as the vaccine becomes available. Doing so will protect you before the flu comes to your community. The flu season can extend into the spring, so it is important to still get vaccinated if you did not do so early in the season.

Make sure you talk to your healthcare provider about which vaccine is right for you.

Who Should Not Get Vaccinated?

At this time, you may not want to get the vaccine if you are allergic to eggs. This is because most vaccines will be made using eggs. Further testing on the H1N1 flu vaccine may indicate that other people need to be cautious as well. Talk to your doctor to learn more.

The nasal spray (live, attenuated vaccine) should not be given to:

Those younger than two years or older than 50 years
Anyone with a severe chronic medical condition or weakened immune system
Pregnant women
Children under 18 years old taking chronic aspirin therapy

Is the H1N1 Flu Vaccine Safe?

Like the seasonal flu vaccine , the H1N1 flu vaccine is not expected to cause problems other than soreness at the injection site. People with specific allergies (eggs, latex, or certain drugs) should check with their doctor before receiving any flu vaccine.

In 1976, a flu vaccine was linked with cases of Guillan-Barre syndrome (GBS) , a rare nerve disease causing weakness for several weeks, with some cases being severe enough to require breathing machines. The rate of GBS related to the vaccine was about 1 case per million vaccine doses. Since 1976, flu vaccines have not been clearly linked with GBS.

What Other Ways Can H1N1 Be Prevented Besides Vaccination?

Wash your hands often, especially when you come in contact with someone who is sick. Wash your hands for 15-20 seconds with soap and water. Rubbing alcohol-based cleaners on your hands is also helpful.
Avoid close contact with people who have respiratory infections. The flu can spread starting one day before and ending seven days after symptoms appear.
Consider using a disposable face mask if you have a high risk of severe illness from the flu and are unable to avoid crowded areas.
Cover your mouth and nose with a tissue when you cough or sneeze. Throw away the tissue after you use it. Coughing or sneezing into your elbow or upper sleeve is also helpful.
Do not spit.
Do not share drinks or personal items.
Do not bite your nails or put your hands near your eyes, mouth, or nose.
Keep surfaces clean by wiping them with a household disinfectant.
Do not use products sold on the Internet claiming to prevent pandemic H1N1 flu. Talk to your doctor before using such products.
The US Centers for Disease Control and Prevention (CDC) recommends that you or your child do not attend swine flu parties.
Talk to your doctor about taking antiviral medicines.

What Happens in the Event of an Outbreak?

The CDC has issued some specific guidelines for public facilities. This will help schools, businesses, correctional facilities, and healthcare settings manage an outbreak of the flu. The advised actions may include isolating infected individuals and cleaning the facility. In some cases, the facility may need to be closed for a period of time.

RESOURCES

Centers for Disease Control and Prevention http://www.cdc.gov/h1n1flu/vaccination/public/vaccination

European Commission—Health Information http://ec.europa.eu/health/ph%5Fthreats/com/Influenza/h1n1%5Fen.htm

European Medicines Agency http://www.emea.europa.eu/

Flu.gov http://www.flu.gov/

Public Health Agency of Canada http://www.phac-aspc.gc.ca/index-eng.php

United Kingdom Department of Health http://www.dh.gov.uk

World Health Organization http://www.who.int/csr/disease/swineflu/

References

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Centers for Disease Control and Prevention. Asthma information for patients and parents of patients. Centers for Disease Control and Prevention website. Available at: http://www.cdc.gov/H1N1flu/asthma.htm . Updated September 15, 2009. Accessed September 15, 2009.

Centers for Disease Control and Prevention. CDC advisors make recommendations for use of vaccine against novel H1N1, July 29, 2009. Centers for Disease Control website. Available at: http://www.cdc.gov/media/pressrel/2009/r090729b.htm . Accessed August 20, 2009.

Centers for Disease Control and Prevention. CDC novel H1N1 vaccination planning Q&A. Centers for Disease Control website. Available at: http://www.cdc.gov/h1n1flu/vaccination/statelocal/qa.htm . Accessed August 20, 2009.

Interim recommendations for facemask and respirator use to reduce novel influenza A (H1N1) virus transmission. Centers for Disease Control website. Available at: http://www.cdc.gov/h1n1flu/masks.htm . Updated August 5, 2009. Accessed September 3, 2009.

NIAID 2009 H1N1 Influenza Research Program. National Institute of Allergy and Infectious Diseases website. Available at: http://www3.niaid.nih.gov/topics/Flu/understandingFlu/2009h1n1.htm . Accessed August 21, 2009.

Novel H1N1 influenza vaccine. Centers for Disease Control website. Available at: http://www.cdc.gov/h1n1flu/vaccination/public/vaccination%5Fqa%5Fpub.htm . Accessed August 20, 2009.

Novel H1N1 flu (swine flu) and you. Centers for Disease Control website. Available at: http://www.cdc.gov/h1n1flu/qa.htm . Accessed August 20, 2009.

Pandemic (H1N1) 2009. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed/what.php . Updated November 24, 2009. Accessed November 25, 2009.

Swine flu on track for September. The Los Angeles Times website. Available at: http://latimesblogs.latimes.com/booster%5Fshots/2009/08/swine-flu-vaccine-on-track-for-september.html . Accessed August 21, 2009.

United States Food and Drug Administration. Influenza A (H1N1) 2009 monovalent vaccines questions and answers. United States Food and Drug Administration website. Available at http://www.fda.gov/BiologicsBloodVaccines/Vaccines/QuestionsaboutVaccines/ucm182335.htm . Updated September 15, 2009. Accessed September 17, 2009.

Revision Information

Reviewer: Brian Randall, MD
Review Date: 10/2012 -
Update Date: 10/31/2012 -

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.