Novel H1N1 Influenza Vaccine

October 16, 2009, 10:45 AM ET

Who will be recommended to receive the 2009 H1N1 vaccine?

CDC's Advisory Committee on Immunization Practices (ACIP) has recommended that certain groups of the population receive the 2009 H1N1 vaccine when it first becomes available. These target groups include pregnant women, people who live with or care for children younger than 6 months of age, healthcare and emergency medical services personnel, persons between the ages of 6 months and 24 years old, and people ages of 25 through 64 years of age who are at higher risk for 2009 H1N1 because of chronic health disorders or compromised immune systems.

We do not expect that there will be a shortage of 2009 H1N1 vaccine, but availability and demand can be unpredictable. There is some possibility that initially the vaccine will be available in limited quantities. In this setting, the committee recommended that the following groups receive the vaccine before others: pregnant women, people who live with or care for children younger than 6 months of age, health care and emergency medical services personnel with direct patient contact, children 6 months through 4 years of age, and children 5 through 18 years of age who have chronic medical conditions.

The committee recognized the need to assess supply and demand issues at the local level. The committee further recommended that once the demand for vaccine for these target groups has been met at the local level, programs and providers should begin vaccinating everyone from ages 25 through 64 years. Current studies indicate the risk for infection among persons age 65 or older is less than the risk for younger age groups. Therefore, as vaccine supply and demand for vaccine among younger age groups is being met, programs and providers should offer vaccination to people over the age of 65.

Will two doses of vaccine be required?

The U.S. Food and Drug Administration (FDA) has approved the use of one dose of 2009 H1N1 flu vaccine for persons 10 years of age and older. This is slightly different from CDC's recommendations for seasonal influenza vaccination which states that children younger than 9 who are being vaccinated against influenza for the first time need to receive two doses. Infants younger than 6 months of age are too young to get the 2009 H1N1 and seasonal flu vaccines.

What will be the recommended interval between the first and second dose for children 9 years of age and under?

CDC recommends that the two doses of 2009 H1N1 vaccine be separated by 4 weeks. However, if the second dose is separated from the first dose by at least 21 days, the second dose can be considered valid.

Do those that have been previously vaccinated against the 1976 swine influenza need to get vaccinated against the 2009 H1N1 influenza?

The 1976 swine flu virus and the 2009 H1N1 virus are different enough that its unlikely a person vaccinated in 1976 will have full protection from the 2009 H1N1. People vaccinated in 1976 should still be given the 2009 H1N1 vaccine.

Can people who are allergic to eggs receive the 2009 H1N1 flu vaccine?

People who are allergic to eggs might be at risk for allergic reactions from receiving influenza vaccines, including the 2009 H1N1 vaccine. People who have had any of the following symptoms or experiences should consult with a doctor or other medical professional before considering any influenza vaccination:

• hives or swelling of the lips or tongue
• acute respiratory distress (trouble breathing) after eating eggs
• documented hypersensitivity to eggs, including those who have had asthma related to egg exposure at their workplace or other allergic responses to egg protein

Because children with severe asthma are at high risk of serious complications from influenza, a regimen has been developed for giving influenza vaccine to children with severe asthma and egg hypersensitivity.