Canadian study that suggests seasonal flu shots raise a person's risk of catching swine flu

By Helen Branswell Medical Reporter (CP)

TORONTO — An unpublished Canadian study that suggests seasonal flu shots raise a person's risk of catching swine flu is causing a lot of concern internationally, a senior official of the World Health Organization said Thursday.

Dr. Marie-Paule Kieny, who heads the WHO's vaccine research initiative, said there's a keen interest, internationally, to go through the data in the study and see whether the research is correct or flawed.

"There's really intense international discussions on that," Kieny told The Canadian Press in an interview.

"Because now that it's out, everybody feels that we must go to the bottom of it and see what's real there."

She noted in a news conference that Canadian officials are trying to put together an expert panel to assess the data.

Drawn from a series of studies from British Columbia, Quebec and Ontario, the findings appear to suggest that people who got a seasonal flu shot last year are about twice as likely to catch swine flu as people who didn't.

A scientific paper has been submitted to a journal and the lead authors - Dr. Danuta Skowronski of the British Columbia Centre for Disease Control and Dr. Gaston De Serres of Laval University - are constrained about what they can say about the work. Journals bar would-be authors from discussing their results before they are published.

Skowronski, who at first declined to speak after news of the findings hit the media Wednesday, said it's important that the work gets the expert scrutiny the journal peer-review system provides.

"Good scientists know that methods can influence results," she said from Vancouver.

"For me, it's very important that we respect the peer-review process as good scientists. Because the implications ... are important. And if there are methodologic flaws, we need to be assured that every stone was turned over to make sure what we're reporting is valid."

The findings are already having implications, with public health officials across the country grappling with whether to delay, reduce or scrap altogether seasonal flu shot programs this year.

Officials from Saskatchewan said Thursday they are leaning towards suspending seasonal flu shot efforts for this fall. But Dr. Joel Kettner, chief medical officer of health for Manitoba, said his province is moving ahead with planning for a rollout soon, though the planning makes room for the possibility they may need to stop the program "on a dime."

Earlier this week officials from Quebec raised publicly the possibility of dropping or delaying seasonal flu shot efforts, saying at the time they hoped for a pan-Canadian approach.

Kettner said he continues to hope all provinces and territories will go the same way on this. But he acknowledged that may not be possible.

While few people appear to have actually read the study, the troubling findings have been a poorly kept secret and many in the public health community in Canada have heard about them.

So have many influenza researchers abroad. Kieny said British, American and Australian researchers have looked for and haven't found similar findings in their data. On Thursday, the U.S. Centers for Disease Control confirmed that via email.

"It is difficult to speak about a study that has yet to be published, however, as this is an important issue involving the subject of seasonal influenza and the fast moving global pandemic of 2009 H1N1 influenza it is important to note the scientists at the Centers for Disease Control and Prevention have not seen this effect in systems we have reviewed in the United States," spokesperson Joe Quimby said.

The Public Health Agency of Canada was informed of the findings some time ago and has been seeking help to try to figure out if the effect is real or the result of flaws in the research.

"An arms-length review of the various methods is currently underway to assess the validity of the studies relative to that observation," Dr. David Butler-Jones, Canada's chief public health officer, said via email.

Kieny said it is important to study the data with an open mind.

"If there is something, it's better that it comes out," she said. "I think one needs to keep open eyes and a fresh mind and look in all fairness to the results."

Still, she, like others, struggled to come up with a reason for why getting a seasonal flu shot would elevate a person's risk of catching swine flu, noting there is no evidence to suggest that getting the flu shot one year raises a person's risk of catching flu the next.

"The plausibility seems sort of in question," she said.

"It may be a study bias. It may be that something is real," Kieny said during the news conference.

"But certainly the WHO as well as the regulators in all of these countries are looking forward to be able to see the data, to study the data and come with a better understanding of whether this has any chance of indeed putting people at risk, the fact that they have received a seasonal vaccination."