Following up on last week’s post, it appears that the H1N1 flu vaccine is effective in older children, ages 10 to 17, based on preliminary results of an ongoing trial. This week, the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, announced that early results of clinical studies of the vaccine “look promising.” Researchers found that a single 15-microgram dose, the same dose as the seasonal flu vaccine, produced a good immune response against the H1N1 virus in children ages 10–17 after eight to 10 days. These early results are similar to the results of adult trials announced by NIAID earlier this month.

As for children under 10, NIAID said they “had a less robust early response to the vaccine” and that this follows the pattern of seasonal flu vaccine responses in younger children. For this reason, it is likely that they will need two doses of the H1N1 flu vaccine.

“These results are not unexpected and are both similar to what is seen with seasonal influenza vaccines and consistent with what we and our colleagues at the Food and Drug Administration anticipated,” NIAID Director Anthony S. Fauci said in the announcement.

Also announced this week, Sanofi Pasteur received an additional order for the H1N1 flu vaccine from the US Department of Health and Human Services. Sanofi will produce an additional 27.3 million doses for the government’s pandemic response plan, bringing the total to 75.3 million doses. Sanofi’s vaccine is used in the children’s vaccine trial, and is one of the four approved by FDA on Sept 15.