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Healthy Kids Won’t Need Second H1N1 Shot

Some parents of small kids dreading the notion of getting back into H1N1 vaccine lineups next week for their child’s second shot got some good news Thursday.

So did their kids.

The Public Health Agency of Canada announced it is changing its recommendation for healthy children aged three to nine, saying they probably don’t need a second shot of the vaccine to be protected.

The decision isn’t based on the hardest of hard scientific evidence, but on some promising data and the reality that when vaccine supplies are still scarce, it probably makes sense to give more people one dose than to give children a second dose they may not need. It’s a position advised by the World Health Organization.

The head of the Public Health Agency, Dr. David Butler-Jones, called the decision “educated pragmatism.”

The agency said kids aged three to nine with chronic diseases may need a second shot. And infants and toddlers aged six to 35 months should get two shots of the vaccine, said Butler-Jones.

“There’s not enough information now to make a blanket recommendation for all groups,” he said in an interview.

“But in consultation with the pediatricians and the vaccine task group … and public health officials across the country, this seems very prudent and reasonable advice because parents are going to be starting to make this decision next week. So we want to get ahead of that.”

The agency reserved the right to revisit the decision in the future if newer scientific data point to a need for two doses for these children, or confirm that one dose would be sufficient even for young kids with chronic illnesses.

Next week marks the fourth week of Canada’s H1N1 vaccination campaign in a number of jurisdictions, so parents who had kids under 10 vaccinated in Week 1 would be starting to plan how and when to get the second needle. When two shots are recommended, there must be at least a 21-day interval between the two.

The limited data that exist suggest the vaccine Canada is using may even protect young children with a single dose because it contains an adjuvant, an additive that boosts the immune response. But the data are too limited for the experts advising Canada on H1N1 vaccine policy to feel confident that the youngest children would be protected by a single shot.

Little kids’ immune systems are not as developed as those of adults, making them both more vulnerable to circulating bugs and less responsive to a single dose of vaccine. In them, vaccines are generally given in at least two doses, one to introduce the immune system to a pathogen – that’s called priming – and a second to “boost” the initial response.

Vaccine expert Dr. David Scheifele of B.C. Children’s Hospital had been among those who didn’t feel one dose of H1N1 vaccine would be sufficient for the little kids. He said Thursday he’s satisfied with the compromise.

“It is sensible in the circumstances,” Scheifele, who is director of the University of British Columbia’s Vaccine Evaluation Centre, said via email.

“I can live with healthy children having to wait for a possible second dose (should it prove necessary) while adults at higher risk obtain vaccine. The issue can be revisited when vaccine supply improves or new data become available.”

Butler-Jones held out hope that even kids three to nine who have chronic illnesses may be able to get away with a single shot, but said a decision on that would have to wait for additional information.

“Once the other high risks groups are done, then they could consider a second shot. And maybe by then we’ll actually have enough information to say: ‘No, you’re good.”‘

But Butler-Jones pretty much squelched the hopes of some parents that they could get unadjuvanted H1N1 shots for their children.

At one point offering unadjuvanted vaccine for children six to 35 months old was under discussion and some parents have been waiting for that option. Butler-Jones said it isn’t on offer.

“The recommendation is under the age of 10, only adjuvanted vaccine. That’s the recommendation” he said.

“I would strongly recommend against that,” he added, when asked what would happen if parents insisted they wanted unadjuvanted vaccine for their children.

“The levels of immunity we’re seeing with adjuvanted vaccine after one half dose in most kids will provide what appears to be even better protection than even two half-doses of unadjuvanted. So why would you subject a kid to twice as much opportunity, plus a longer period before they’re actually immune?”

Scheifele had initially voiced some concern about using adjuvanted vaccine in the youngest children. But he appears to have changed his position.

“As the evidence accumulates for the superiority of the adjuvanted vaccine, it’s hard to make a case for using the other stuff,” he said.

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