Photo Credit PHIL
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We’ve another chapter today in the ongoing saga of what became known as the `Canadian Problem’ – which began in the summer of 2009 when news of several unpublished Canadian studies emerged suggesting prior seasonal flu vaccination made you more at risk of contracting the 2009 Pandemic virus.
At the time, delivery of the pandemic vaccine was still several months away - and plans were to roll out the seasonal vaccine first – to protect against non-pandemic strains.
Helen Branswell, science and medical reporter for the Canadian Press, was among the first to report on it (see Branswell On The Canadian Flu Shot Controversy).
Suddenly, there was genuine concern that with a pandemic virus on the way, that rolling out the seasonal vaccine might be the wrong thing to do.
The CDC and the World Health Organization both scrambled to look at their available data, and stated that they could find no correlation between the seasonal vaccine and susceptibility to the pandemic flu . . . but that they would continue to look.
Meanwhile, with concerns rising, a number of Canadian Provinces halted or announced delays in their seasonal flu shot campaign, even though the study had yet to be published (see Ontario Adjusts Vaccination Plan).
October saw a number of new reports and studies that failed to corroborate the (still unpublished) findings, including a study published in the BMJ (British Medical Journal) that suggested exactly the opposite - that getting the seasonal flu vaccination may be slightly protective against the swine flu (see When Studies Collide).
By November, with no compelling corroboration of the `Canadian Problem’, Canada’s National Advisory Committee on Immunization (NACI) came out in favor of resuming seasonal flu jabs (see NACI: Canada Should Resume Seasonal Flu Vaccinations).
The controversy wasn’t over, however.
In April of 2010 these Canadian studies were finally published by PLoS Medicine. Writing for CIDRAP, Maryn McKenna detailed their findings.
New Canadian studies suggest seasonal flu shot increased H1N1 risk
Maryn McKenna
Contributing Writer
Apr 6, 2010 (CIDRAP News) – Despite a rapidly launched range of studies, investigators in Canada are still unable to say—or to rule out—whether receiving a seasonal flu vaccination in the 2008-09 season made it more likely that Canadians would become ill from 2009 pandemic H1N1 flu.
But other studies (see 2010 Eurosurveillance On `The Canadian Problem’ and 2012’s EID Journal: Revisiting The `Canadian Problem’) failed to find a correlation.
While most studies have shown no causal link between receipt of the seasonal vaccine and contracting the 2009 H1N1 virus, the results have not been 100% in alignment.
All of which serves as prelude to a fascinating video interview today of Dr. Danuta Skowronski, who was involved in the original Canadian studies, and who has apparently duplicated the vaccine effect using ferrets in a double-blind study.
In this study, they took 32 ferrets and under `blinded’ conditions gave half the seasonal vaccine, and half a placebo. They later exposed all of them to the H1N1 pandemic virus, and followed them for 14 days to see how they responded.
The ferrets that had previously received the seasonal vaccine suffered longer and greater illness than those who received the placebo, although all eventually recovered.
Dr. Skowronski believes these results may be unique to the 2009 pandemic – which quite unusually involved a antigenically shifted H1N1 virus, similar to a strain that had been in circulation for decades.
So she strongly advises that people continue to get the seasonal flu vaccination.
For more on all of this, we turn to Helen Branswell, who can always be depended upon to provide terrific coverage.
Flu shot issue dismissed as a 'Canadian problem' may not be so, study suggests
Helen Branswell, Sunday, September 09, 2012
TORONTO – A strange vaccine-related phenomenon spotted at the start of the 2009 flu pandemic may well have been real, a new study suggests.
Canadian researchers noticed in the early weeks of the pandemic that people who got a flu shot for the 2008-2009 winter seemed to be more likely to get infected with the pandemic virus than people who hadn’t received a flu shot.
Although the mechanism behind this reported effect isn’t clear, one of the two main theories being considered is called the The Temporary Immunity Hypothesis, which we looked at back in November of 2010. The subject came up again February of 2011, in Flu Vaccines & The Temporary Immunity Hypothesis.
While today’s report certainly adds intriguing findings to an already fascinating story, we’ll have to wait for more research before we’ll know the full extent and cause of the `Canadian Problem’.
