Now that it has been about five weeks since H1N1 vaccine began trickling out, parents of some children, those lucky enough to have received their first dose, are wondering how they're going to get the second dose needed to fully protect their kids.
Last week, the Park Nicollet Clinic, a large medical practice based in St. Louis Park, Minn., began telling parents that boosters would have to be postponed because of the H1N1 vaccine shortage.
The federal government had said it expected to receive 200 million doses by the end of the year. One week into November, it had only 38 million.
Officials at Park Nicollet, whose H1N1 vaccine clinics are open to the public, felt it was more important to give at least one dose to as many children as possible, says Joan Sandstrom, vice president of primary care and behavioral health.
"I wouldn't be at all surprised that, as time goes on, they'll be able to say that one dose will be enough," says Sandstrom, a nurse. "That clearly went into our decision."
The World Health Organization advises giving one dose to as many children 6 months through 9 years of age as possible but notes that recommendations on numbers of dosages may change as new data emerge.
U.S. government flu experts say it's unlikely their current recommendation of two doses for children 6 months to 9 years old will change.
Clinical trials have shown that kids in that age group tend not to mount an adequate immune response after only one dose of the vaccine used in the USA.
In Canada and Europe, H1N1 vaccine contains an adjuvant, a substance designed to boost the immune response, but no approved U.S. flu vaccine has ever contained one.
"There's no doubt that in the younger children, 6 months to 9 years, the studies that we did indicated you got a suboptimal response" with one dose, Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said Tuesday. "Should you get the second dose? If possible, absolutely. Does that mean that one dose is useless? Absolutely not."
Some children will have an adequate immune response with a single dose, but that's much more likely in older children and adults, Fauci says. Generally, he says, even a suboptimal response is better than no response, suggesting that young children who get sick with H1N1 after one dose might have a milder case of the flu. But studies haven't been done to confirm that's true with H1N1.
Giving one dose to as many kids as possible before providing the booster is "reasonable," says Anthony Fiore of the CDC's influenza division. But usually, Fiore says, with vaccines, "you never turn them away. They might not ever come back again."
The clinical trials scheduled H1N1 vaccine doses three weeks apart for children, but waiting five or six weeks is fine, Fiore and Fauci say -- as long as parents do return for a second dose.
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