WINNIPEG — Aboriginal people are able to ward off the H1N1 flu virus as well as or better than the rest of the population, a University of Manitoba study says — a finding that contradicts the theory that put aboriginals at the head of the line for the vaccine last year.

Aboriginal people were given priority for the H1N1 vaccine in 2009 and were required to get two dosages instead of the single shot other Canadians received.

"The results point out that aboriginal people are not deficient in their immune response to H1N1," said Dr. Ethan Rubinstein, the lead researcher and a member of the U of M's infectious diseases section.

The study tested the immune response of 120 aboriginal people from Manitoba. The subjects were from large population centres, like Winnipeg and Portage la Prairie; none of them were from the northern reserves which experienced severe flu outbreaks in the past year.

"The results show they reacted beautifully to the vaccine," Rubinstein said. "If another wave comes, one vaccine would be sufficient."

Rubinstein said that while the study was based on a small sample, there was little variation in the results.

The first wave of H1N1 in spring of 2009 showed shockingly high infection rates among northern aboriginal people. That prompted health officials in many provinces to allow them to be among the first vaccinated, with a second dose recommended for four weeks later.

"It was a theory that was out there and we disproved it," said Rubinstein. "Other explanations have to be given for why they became so sick."

Rubinstein wouldn't speculate what might have driven the higher infection rates in some aboriginal communities.

A study released in January found that 60 per cent of Manitoba's severe H1N1 cases for 2009 affected First Nations people.

That study also found that the likelihood of severe infection was related to delays in receiving antiviral treatment.

It had drawn a parallel between First Nations populations and Aboriginals in Australia and New Zealand, who were also both overrepresented by severe H1N1 infections in 2009, a finding attributed to social conditions.

The University of Manitoba study will be presented to the ninth annual Canadian Immunization Conference in Quebec City next month.

bill.redekop@freepress.mb.ca