Influenza vaccine is the best way to protect against getting sick with H1N1 influenza (the flu). Vaccination helps the body’s ability to fight off influenza infection and stay healthy. It is especially important for people at high risk for serious illness due to flu and for their close contacts to be vaccinated.

Most healthy people who get H1N1 influenza have a mild illness lasting about a week. But young children, pregnant women, and people with certain chronic medical conditions (see next question) are at an increased risk for severe illness that can lead to hospitalization and sometimes death. Even a mild case of the flu can be very uncomfortable and result in missed days of work and school. As more people get vaccinated against the flu, the less flu will spread in the community. Vaccination helps protect those who are at greater risk of serious illness.

Do I still need to get vaccinated if I have already been sick?

Yes. Unless you were tested specifically for the H1N1 flu virus, you don’t know if that’s what made you sick. Getting vaccinated against H1N1 influenza will help protect you and others in case what you already had was not the H1N1 flu.

Who can get the H1N1 influenza vaccine?

The H1N1 vaccine is now available for anyone in the general population who wants one. Vaccine supply is abundant as of January 2010.

Who is most at risk?

The H1N1 vaccine continues to be most important for those who are at the highest risk of severe illness, which includes the following:

Pregnant women
Children under 5 years of age
People with chronic health conditions (such as asthma, heart disease, diabetes, or brain and nervous system disorders)

How safe is the H1N1 influenza vaccine?

The H1N1 influenza vaccine is being manufactured using the same processes and testing as seasonal flu vaccines. The Centers for Disease Control and Prevention (CDC) reports the H1N1 influenza vaccine to be as safe as seasonal flu vaccines, which have an excellent safety record. Over the years, hundreds of millions of Americans have safely received seasonal flu vaccines, as have millions more worldwide. As of January 2010, 61 million Americans have received the H1N1 vaccine.

Testing for the H1N1 influenza vaccine seems like it was very quick. Was the testing adequate to produce a safe vaccine?

No corners were cut in the development and testing of H1N1 influenza vaccine. The H1N1 influenza vaccine was developed using the same manufacturing processes as seasonal flu vaccines and had even more testing than seasonal flu vaccines. In fact, if the H1N1 influenza had started circulating earlier—before this year’s flu shot was developed—it would have been included in this year’s regular flu shot like any other flu strain.

The clinical trials (tests of the vaccine on humans) for H1N1 have not shown any unusual or unexpected side effects and new side effects from H1N1 vaccine are not anticipated. Because rare side effects can only be detected after very large numbers of persons have been vaccinated, there are monitoring systems in place to detect any unexpected rare side effects now that the vaccine is in wide use.

Should pregnant women get the H1N1 vaccine?

Yes. It is very important for a pregnant woman to get the H1N1 influenza vaccine as well as a seasonal influenza vaccine. A pregnant woman who gets any type of flu is at risk for serious health complications and hospitalization. Pregnant women infected with the H1N1 influenza virus are much more likely than other flu patients to require hospitalization. In addition, severe illness and death from H1N1 has occurred in pregnant women, even those who were previously healthy.

Handwashing and avoiding people who are ill can help protect pregnant women from influenza, but vaccination is the single best way to protect against the flu.

Is there a particular kind of flu vaccine that pregnant women should get?

There are two types of flu vaccine. Pregnant women should get the injectable “flu shot” that is given with a needle, usually in the arm. The flu shot is approved for use in pregnant women. The other type of flu vaccine — nasal-spray flu vaccine (FluMist) — is a weakened live virus vaccine that is not routinely given to pregnant women.

Multi-dose vials (used to store injectable flu vaccine) contain the preservative thimerosal, which contains a very small amount of mercury. There is no evidence that thimerosal is harmful to a pregnant woman or a fetus. However, because some women are concerned about exposure to preservatives during pregnancy, manufacturers are producing preservative-free seasonal flu vaccine and 2009 H1N1 flu vaccine in single dose syringes. CDC recommends that pregnant women receive flu vaccine with or without thimerosal.

How many shots will children need of the H1N1 vaccine?

One dose of the H1N1 flu vaccine is approved for persons 10 years of age and older. Two doses of the vaccine are recommended for children 6 months through 9 years of age. The two doses should be timed at least 4 weeks apart. Infants younger than 6 months of age are too young to get the H1N1 and seasonal flu vaccines.

Are the seasonal flu vaccine and the H1N1 influenza vaccine the same thing?

No. The H1N1 influenza vaccine only protects against the H1N1 (swine flu) virus. It will not protect against other influenza strains that may cause seasonal flu this season. The seasonal flu vaccine does not protect against H1N1 influenza. Seasonal flu vaccine is available from many pharmacies and healthcare providers now.

Can I get a seasonal flu vaccine and an H1N1 vaccine at the same time?

Yes, in most cases. The exception is getting a seasonal influenza FluMist vaccine and an H1N1 influenza FluMist vaccine at the same time—you cannot get these two nasal spray vaccines together. Otherwise, getting two at the same time works for most people. Speak with your health care provider to check if this is right for you.

Will I get the flu from the H1N1 flu vaccine?

No, flu vaccines cannot cause the flu. The viruses contained in flu shots are inactivated (killed), which means they cannot cause infection. In randomized, blinded studies, where some people got flu shots and others got saltwater shots, the only differences in symptoms was increased soreness in the arm and redness at the injection site among people who got the flu shot. There were no differences in terms of body aches, fever, cough, runny nose or sore throat in both study groups.

The nasal-spray flu vaccine contains a weakened live flu virus that is designed to cause a mild infection of the nose and throat to produce immune system protection against serious flu virus infections. In children, possible side effects can include runny nose, headache, wheezing, vomiting, muscle aches and fever. In adults, possible side effects can include runny nose, headache, sore throat and cough. Fever is not a common side effect in adults receiving the nasal-spray flu vaccine.

Once when I got the flu shot, I thought it gave me the flu. Is this possible?

No. But there are several reasons why someone might get flu-like symptoms even after they have been vaccinated against the flu:

People may be exposed to an influenza virus shortly before getting vaccinated or during the two-week period that it takes the body to gain full protection after getting vaccinated. This exposure may result in a person becoming ill with flu before the vaccine begins to protect them.
People may become ill from other (non-flu) viruses that circulate during the flu season, which can also cause flu-like symptoms (such as rhinovirus which cause the common cold). These viruses may cause you to feel ill, but are less serious than influenza.
A person may be exposed to an influenza virus that is not included in the vaccine they received. There are many different influenza viruses. H1N1 influenza vaccine will only protect against the H1N1 strain of influenza.
Seasonal flu vaccine will protect against other strains of influenza that health experts predict will be in circulation, but it's possible that the seasonal flu vaccine will not include all the circulating strains because vaccines must be manufactured months before the flu season starts.
Unfortunately, some people can remain unprotected from flu despite getting the vaccine. This is more likely to occur among people that have weakened immune systems. However, even among some people with weakened immune systems, the flu vaccine can often help prevent more severe illness from influenza.

How long does the H1N1 influenza vaccine provide protection?

The vaccine will only provide protection for one flu season. Next year, the H1N1 influenza virus will likely be one of the viruses included in the seasonal flu vaccine.

What are potential side effects from the H1N1 vaccine?

Most people will not experience side effects. If side effects occur, they will likely be similar to the mild side effects some people have with seasonal influenza vaccine. These side effects usually begin soon after the shot and last 1-2 days. In adults, the main side effect is soreness, redness or swelling in the arm where the shot was given. A small fraction of children who get influenza vaccine may develop mild fever and/or muscle aches.

As with any medicine, there is a very small chance that an unexpected or severe allergic reaction may occur, but serious problems from the flu vaccine are very rare. The risk from the vaccine is much smaller than the risk from the disease. However, if you have a severe (life-threatening) allergy to chicken eggs or to any other substance in the vaccine, you should not be vaccinated.

Is the thimerosal in the H1N1 vaccine safe?

Thimerosal, a mercury preservative in vaccine that comes in multi-dose vials, is used in vaccines to prevent bacterial contamination. Although some people are concerned about health risks from thimerosal, it has never been shown to cause any health problems. An exhaustive 2004 report by the Institute of Medicine of the National Academies of Science concluded that thimerosal in vaccines does not cause health problems, a conclusion also reached by other countries around the world. The American Academy of Pediatrics, the U.S. Centers for Disease Control and Prevention and the Institute of Medicine have concluded, based on scientific data, that thimerosal-containing vaccines are safe.

Can I get a thimerosal-free H1N1 influenza vaccine?

Some H1N1 influenza vaccines are available in thimerosal-free formulations, including the nasal-spray vaccine. However, the majority of influenza vaccines do contain small amounts of thimerosal as a preservative to prevent bacterial contamination.

Where can I get H1N1 influenza vaccine?

See Where to Get Vaccinated»

How much will the H1N1 influenza vaccine cost?

The H1N1 vaccine is provided free of cost by the federal government, but the office or organization that gives the shot may charge an administration fee for giving the vaccine (likely to be around $15). Most insurers will reimburse these costs. No administration fee is being charged at public vaccination clinic sites, where the vaccine is free.

Can I still get it if I don’t have health insurance?

There are opportunities to get vaccinated for people without health insurance and who can’t afford to pay. These public clinic locations are publicized on local and state public health Web sites.

I am not a U.S. citizen. Can I still get the vaccine?

Yes. Preventing the spread of influenza throughout our entire community is important so vaccine will be given to everyone, regardless of citizenship.

More Information

H1N1 Hotline
1-800-978-3040 toll-free

• Talk to someone about H1N1
• Get vaccine info and locations

Oregon Public Health
www.flu.oregon.gov

Centers for Disease Control &
Prevention
1-800-CDC-INFO (232-4636)
1-888-232-6348 TTY
www.cdc.gov/h1n1flu
Email: cdcinfo@cdc.gov

World Health Organization
www.who.int/csr/disease/
swineflu/en/index.html

Contact Us

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503-988-3816

Administration
Multnomah County Health Department
426 SW Stark St, 8th Floor
Portland, OR 97204

503-988-3674
503-988-3676 fax
1-877-735-7525 TDD

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Page updated February 4, 2010