World Health Organization says a single dose of H1N1 vaccine may be sufficient, even for children

Ian Sanders, 10 1/2 months, is held by his parents after receiving a flu shot in Fairfax.
Ian Sanders, 10 1/2 months, is held by his parents after receiving a flu shot in Fairfax. (Tracy A. Woodward/the Washington Post)
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By Rob Stein
Washington Post Staff Writer
Saturday, October 31, 2009

One dose of vaccine might be enough to protect both adults and children older than six months against the swine flu pandemic, an international panel of experts has concluded.

The experts, convened by the World Health Organization to review global data on the various vaccines being tested and used to stem the pandemic, recommended that countries that have made children a high priority for the vaccine should consider giving one dose to as many children as possible before administering a second dose.

U.S. health officials have recommended two doses for children younger than 10, based on the early results of studies indicating that one dose was insufficient to produce a strong enough immune system response to protect that age group.

The WHO's Strategic Advisory Group of Experts acknowledged that data on that age group was "limited and more studies are needed." It said each country should decide what strategy is most appropriate for its population. Giving two shots is safe, the experts said.

"Different regulatory authorities have made different decisions," Marie-Paule Kieny, director of the WHO's Initiative for Vaccine Research, said at a briefing Friday for reporters at the conclusion of the advisory group's two-day meeting in Geneva.

"But for the time being for the countries who want to do a very large vaccine campaign in children, . . . the number of doses of vaccine may not be sufficient to provide two doses to these children," Kieny said.

The National Institutes of Health is expecting additional results from tests of the vaccine involving children as early as next week that should help clarify whether a booster is needed, said Thomas Frieden, director of the federal Centers for Disease Control and Prevention. "If the data shows a difference, we will revise our recommendation," he said.

The recommendation came as the number of U.S. children who have died from the H1N1 virus increased to 114 -- a jump of 19 deaths from the week before. Unlike the typical seasonal flu, which tends to hit the elderly the hardest, the H1N1 virus has largely spared the elderly but more commonly affected children and young adults, including some who are otherwise healthy.

The CDC also announced plans Friday to release the remaining 234,000 courses of liquid Tamiflu from the federal government's Strategic National Stockpile to help alleviate spot shortages of the antiviral medication. The liquid form of the medicine, most commonly used by children, who can have difficulty swallowing capsules, has been hard to find in some places because of increased demand and a decision by the manufacturer to focus on producing the medication in capsule form. Pharmacists can use the capsules to make the liquid version for individual customers. The CDC released 300,000 courses of the medication on Oct. 1 to try to prevent shortages.

The WHO panel also concluded that every vaccine that has been approved by a government regulatory authority around the world appeared safe, including for pregnant women. That includes vaccines with a substance known as an "adjuvant," which boosts the effectiveness of the vaccine, allowing available stocks to be divided into more doses.

Despite an emergency program to produce the vaccine in the United States and elsewhere, demand for the vaccine so far has outpaced supply in many countries. The United States has not yet approved any vaccine that includes an adjuvant.

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