Young Children May Need Two Vaccines for H1N1

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According to the interim report for a recent trial, children younger than 10 will probably need two doses of the H1N1 (swine flu) vaccine for optimal protection.

Two previous trials by the National Institutes of Health (NIH) and the National Institute of Allergy and Infectious Disease (NIAID) found that just one dose of the H1N1 vaccine would be sufficient to provide immunity after just 8 to 10 days. Those studies focused on healthy adults between age 18 and 64.

The most recent study is the first done on children under the age of 10 and included 474 children. Three groups were given a 7.5 microgram dose, a 15-microgram dose, or a placebo. Their immunity response was measured after 21 days.

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Of the children receiving the 15-microgram dose, 76% of those age 3 to 9 years old had immune responses considered seroprotective, meaning protection from the virus was obtained from the vaccine. Only 50% of those 6 to 35 months old had protective responses.

The CDC Advisory Committee has prioritized children and adults younger than 25 for the first round of H1N1 vaccines, along with pregnant women, healthcare and emergency medical services personnel, caregivers of children under 6 months, and adults under 65 with certain chronic medical conditions.

The most recent data from the CDC 2009 H1N1 reports, influenza activity continues to increase across the United States, with activity in 37 states. A total of 250 million doses of the vaccine were initially purchased and have begun distribution as of early October. An additional 40 million doses are expected by the end of October.

The CDC states that it expects that enough H1N1 vaccines will be available for anyone who chooses to get vaccinated, even with the additional dosage needed for younger children. The second dose of vaccine should be given approximately 4 weeks after the first dose, per the new recommendations.

Sources Include: MedPage Today and The Centers for Disease Control and Prevention.

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