As the H1N1 vaccine is released, health officials recommend that all young people receive the immunization. Drs. Keith English and Steven Buckingham of Le Bonheur’s Infectious Disease department answer questions about the safety of the vaccine, the number of doses children will need and who should receive which type of the vaccine.

While most children infected with the novel H1N1 2009 influenza virus have had mild and self-limited disease, some children have had severe or life-threatening infections. Unlike seasonal influenza, the currently circulating novel H1N1 influenza virus has caused more severe disease in children than in the elderly. Vaccination affords the best possible protection and our best defense to limit the spread of this new flu virus.

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How was the novel H1N1 flu vaccine developed?
The vaccine against the novel H1N1 influenza virus was developed and manufactured exactly the same way that vaccines against seasonal influenza are developed and manufactured every year in this country. In fact, if the virus been circulating last winter (instead of in April and May of this year), it would routinely have been added to the yearly influenza vaccine. The only reason it is being given as a separate vaccine is that this virus was not detected until the spring of 2009 and manufacture of the vaccine against this virus could not be completed in time to add it to the seasonal influenza vaccine.

How will the vaccine protect my child from the H1N1 virus?
Like other influenza vaccines, this vaccine stimulates an immune response against components of the virus. This protects against subsequent infection with the flu virus.

How has the vaccine been tested? What were the results?
The National Institutes of Health (NIH) conducted clinical trials in humans to evaluate the immune response and safety profile of the H1N1 vaccine. Research indicates that the vaccine developed against this worldwide strain is safe and will be highly protective against the circulating H1N1 virus.

What are the side effects, if any?
The Centers for Disease Control and Prevention expects that any side effects following vaccination with the 2009 H1N1 influenza vaccine will be rare. If side effects occur, they will likely be similar to those experienced following seasonal influenza vaccine. Mild problems that may be experienced include soreness, redness or swelling where the shot was given, fainting (mainly in adolescents), headache, muscle aches, fever and nausea. If these problems occur, they usually begin soon after the shot and last 1-2 days. Serious allergic reactions to vaccines are very rare. When they do occur, they usually occur within a few minutes to a few hours after the vaccine is given.

In what form will the vaccine be offered? How do I know which version my child needs?
Just as in the case of the seasonal flu vaccine, the H1N1 vaccine will be available in two different versions:

1. An injectable form that can be given to anyone 6 months of age or older.
2. A nasal-spray (FluMist®) version of the vaccine (live attenuated influenza virus or LAIV) that can be given to people 2 to 49 years of age who are healthy and not pregnant.
   Your children’s physician or health care provider should advise as to which version of the vaccine that your child should receive.

Should all children get the vaccine, or only those in high-risk groups?
All children 6 months of age or older should be immunized against the novel H1N1 influenza virus (and against seasonal influenza) unless they meet one of the specific exclusion criteria listed below.
Who should NOT receive either of the vaccines for H1N1 influenza?
The vaccine should not be administered to the same individuals who should not receive the seasonal influenza vaccine:

• Children younger than 6 months of age
• Anyone with a severe allergy to chicken eggs or anyone who is allergic to any of the components of the influenza vaccines
• Anyone with a history of Guillain-Barré syndrome

Children who are moderately or severely ill are advised to wait until they recover to receive the vaccine. However, for children with a mild cold or other illness, there is usually no need to wait.

Which children should NOT receive the nasal-spray (FluMist®) version of the H1N1 vaccine?
The vaccine should not be administered to the same individuals who should not receive the nasal-spray (FluMist®) version of the seasonal influenza vaccine.

• Children under 2 years of age
• Children under 5 years of age with a history of recurrent wheezing
• Pregnant women
• People with a medical condition that places them at high risk for complications from influenza, including those with chronic heart or lung disease such as asthma or reactive airways disease; people with medical conditions such as diabetes or kidney failure; or people with illnesses that weaken the immune system, or who take medications that can weaken the immune system.
• Children or adolescents receiving aspirin
• People who are in contact with others with severely weakened immune systems when they are being cared for in a protective environment (for example, people with bone marrow transplants). People who have contact with others with lesser degrees of immunosuppression (for example, people with diabetes, people with asthma taking corticosteroids, or people infected with HIV) can get LAIV (FluMist®).
• Anyone with a severe allergy to chicken eggs or anyone who is allergic to any of the components of the influenza vaccines
• Anyone with a history of Guillain-Barré syndrome

How many doses will my child need?
Children 10 and younger will need two doses of the H1N1vaccine. The CDC recommends that the two doses be separated by 4 weeks. Anyone over the age of 10 just needs one dose.

Why wasn’t this vaccine part of the "regular" seasonal influenza vaccine?
The influenza strains to be included in the seasonal ("regular") flu vaccine are selected several months ahead of the flu season, because vaccine viruses only grow slowly in the laboratory. The novel H1N1 flu virus was not detected until after this year's seasonal flu vaccine strains had been selected and development of that vaccine was already underway.

Where and when will the vaccine be available?
Because of the demand for both the seasonal and H1N1 vaccines, there has been limited availability. More vaccines will be available as manufacturers release the doses. Contact your pediatrician of the health department for more information. Also, the Memphis and Shelby County Health Department has a H1N1 hotline at 901.379.H1N1 that is open from 8 a.m.-4:30 p.m., Monday-Friday.

Can the seasonal flu vaccine and the 2009 H1N1 vaccine be given together?
The injectable form of 2009 H1N1 vaccine can be administered at the same time as the injectable OR nasal-spray (FluMist®) version of the seasonal influenza vaccine.

Similarly, it is OK to give the nasal-spray (FluMist®) version of the 2009 H1N1 vaccine at the same time as the injectable version of the seasonal influenza vaccine.

However, the two different nasal-spray (FluMist®) vaccines for the 2009 H1N1 and seasonal influenza viruses should not be administered at the same time. If nasal spray vaccines are used for both 2009 H1N1 vaccine and seasonal flu, the doses should be separated by at least 4 weeks.

If my child has had the H1N1 2009 influenza, is the vaccine necessary?
Anyone who has definitely had the H1N1 2009 influenza is likely immune to the virus and does not require the H1N1 vaccine. However, this can only be known for certain if your child was tested for the H1N1 flu and the test was positive.

If your child had flu, but was not tested, the vaccine is recommended to ensure protection against the H1N1 virus. Even if your child has had documented H1N1 infection, the H1N1 vaccine is safe and should help boost the immune response to the virus.

If my child has recently been treated with Tamiflu® or Relenza® for influenza – is the vaccine still needed?
Yes, your child should still be vaccinated. Tamiflu® and Relenza® are anti-viral medicines that treat infection. Antiviral drugs do not give long term protection against influenza like that provided by vaccines.