The jury is still out on whether there will be a change in the recommendation on how many H1N1 shots children need, the head of the Public Health Agency of Canada suggested Tuesday.
But a vaccine expert said he would be uncomfortable with a decision to move to a single dose for toddlers, saying it would be unwise to assume all Canadian kids would respond to vaccine in the way a very small group of Spanish children did in a clinical trial.
"I think it takes almost magical thinking to imagine that we can generalize those limited data from Spain to a Canadian population," said Dr. David Scheifele, director of the University of British Columbia's Vaccine Evaluation Centre.
Scheifele, who is based at B.C. Children's Hospital, said the only data currently available is a study of 51 young children in Spain who received GlaxoSmithKline's adjuvanted H1N1 vaccine. Canada is also using GSK's vaccine with an adjuvant, an additive that boosts one's response to the serum.
The study showed that even at the youngest age group, kids six months to 35 months, one shot generated antibody levels that are predictive of protection.
Based on those promising results, Public Health Agency head Dr. David Butler-Jones said there might be a possibility kids could be immunized with a single shot, not the two currently recommended.
But he said Tuesday that the agency is not yet ready to make that call.
"(It's a) very small sample," said Butler-Jones, Canada's chief public health officer.
"So we're reviewing not only that data but expert opinion - pediatricians, others, experts in vaccine - and we hope to have a recommendation shortly, certainly in time before anybody needs to consider a second dose. Which will be coming in the next couple of weeks."
In fact, children who were vaccinated in the first days of the vaccination program are closer to their second dose than that.
The recommendation is that the two shots be given 21 days apart. With this week marking the third week of the effort, parents and young kids could be lining up again next week for a second shot.
Scheifele believes at least the youngest children ought to get two shots. They are the ones whose immune systems have the least experience with flu viruses. They are also the ones being hit hardest by this particular virus, he said.
"Ideally it would be the under fives being offered a second dose, but I could live with the under threes."
Scheifele noted the children in the clinical trial were healthy, and their response to vaccine doesn't necessarily predict how First Nations children, children who were born prematurely, who have chronic illnesses or who are malnourished due to poverty or disease will respond to the vaccine.
"So I would guess at least 20 per cent of the Canadian population of young children may not behave the way those selected Spanish kids did," he said.
