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Report: Lab test indicates second H1N1 vaccine shot unnecessary for childre

Category: Infectious Diseases

As scientists continue to refine the H1N1 flu vaccine and examine its appropriate applications, a team of Australian researchers have suggested that a single dose of the shot may be enough to protect infants and children from potential infection, according to clinical tests.

The U.S. Centers for Disease Control and Prevention currently recommends that children and infants receive a second dose of the vaccine about a month after the first inoculation.

As with the vaccine for seasonal flu, the first dose of the H1N1 shot prepares the child's immune system for second dose, which then forces the buildup of enough antibodies to protect against future infection.

However, a report published in the December 21 online edition of the Journal of the American Medical Association reveals data suggesting the second shot may be unnecessary in small children, HealthDay News reports.

The team of researchers, led by Dr Terry Nolan, head of the Department of Public Health at the University of Melbourne, tested the impact of the swine flu vaccine in 370 infants and children between 6 months and 9 years old.

Specifically, the scientists randomly assigned the children to two groups, one slated to receive two injections of 15-microgram doses, the other getting two injections of 30-microgram doses. FDA-approved vaccines administered in doctors' offices and health clinics are usually given in 7.5 microgram doses.

According to Nolan, 92.5 percent of the children who received 15-micrograms of the vaccine and 97.7 percent who were given the 30-microgram dose produced enough antibodies to the swine flu strain to protect them from the virus after a single shot.

HealthDay News reports that the strong immune response appeared regardless of age, previous antibody status or whether the child had previously received the seasonal flu shot.

"It does appear that a single dose is to be very likely all that is required, even for babies," Nolan told the news source. "It's logistically simpler, it's half the cost and for those unable to get the two doses, there are obvious advantages."

He added, "In addition, there is nothing to be concerned about in terms of safety or reaction rates to the vaccine."

Changing recommendations?

Dosage recommendations for the shot have received plenty of public attention recently, after Sanofi Pasteur, a manufacturer of the vaccine, last week recalled about 800,000 doses of their product after tests showed their potency did not meet standard levels.

According to the company's spokesman Len Lavenda, testing showed that the potency of the doses in question, which were intended for young children between the ages of 6 months and 35 months, was about 12 percent less potent than the required levels, CNN.com reports.

A statement by the CDC concluded, "the vaccine in these lots is still expected to be effective in stimulating a protective response despite this slight reduction in concentration of antigen."

However, despite the successful treatment of children with two shots of reduced potency and a single stronger shot, health officials don't appear compelled to change their recommendations.

Dr Anthony Fiore, an epidemiologist in the influenza division at the CDC, addressed the recent Australian study to HealthDay News saying, "Don't relax based upon this study, thinking they don't need that second dose, because they really do to be certain and provide a level of an immune response that we are more confident is going to protect them."

Cases trending downward

Though the vaccine's application remains a point of contention among health officials, the current standards seem effective.

According to the CDC, only 14 states reported widespread swine flu activity in November, down from at 48 states in October.

There are more than 85 million doses of the swine flu vaccine available, HealthDay News reports.