As if there wasn’t already enough resistance to public health officials’ entreaties to vaccinate against the H1N1 virus, an unreleased Canadian study has now cast doubt on whether it’s safe to get the seasonal flu vaccine .

The study indicated taking seasonal vaccine could double the likelihood of contracting H1N1, leading all but one Canadian province to curtail seasonal flu vaccinations. However, the rest of the world has been skeptical of the results, which researchers in Britain, the United States, and Australia have not been able to reproduce.

“Most people are still looking at this as some sort of undetected confounding in the data, that for some reason is giving the results that are there,” David Wood of the World Health Organization told CBC News Friday.

The Canadian authors combined other studies for a total sample size of around 12 million people that included a total of about 2,000 confirmed H1N1 cases from British Columbia, Ontario, and Quebec, according to reports in the Wall Street Journal and Toronto Globe and Mail. They found those who had gotten seasonal flu vaccine last year were about twice as likely to contract H1N1. Although an independent panel and WHO experts found no methodological errors in the study, the lack of replication in other countries means planned side-by-side vaccinations are likely to continue outside Canada.

“WHO is not issuing any general warning about seasonal-flu vaccine,” spokeswoman Aphaluck Bhatiasevi told the Wall Street Journal after WHO reviewed the findings last week.

Adding to the study’s controversy is a cloak of secrecy surrounding the report, which is under peer review by an unnamed journal. The publication process has kept the study’s researchers, Danuta Skowronski of the British Columbia Center for Disease Control and Gaston De Serres of Laval University, from commenting openly, although they were part of the WHO review, according to the Wall Street Journal.

The study was initially met with doubt in Canada, but the credibility of the researchers caused cautious provincial health officials to delay seasonal flu vaccination for people under 65, according to the Toronto Globe and Mail.

Because H1N1 is likely to be this winter’s predominant flu strain and because seasonal flu vaccine can be given once H1N1 vaccinations are complete, there wasn’t a lot of reason to take chances, British Columbia Health Officer Perry Kendall told the Wall Street Journal.

“[It] wasn't something we felt we could ignore,” he said. “Why would you want to run the risk of doubling peoples' risk of getting H1N1?”