VANCOUVER - Another round of fighting has erupted between British Columbia's nurses and its health officer after a U.K.-based, non-profit scientific group publicly questioned the evidence used to justify a mandatory flu-shot policy for provincial health-care workers.

Citing a letter in a Vancouver newspaper written by a doctor associated with group known as the Cochrane Collaboration, the BC Nurses' Union announced Wednesday it has launched a formal grievance over the policy, while also demanding its immediate withdrawal.

But Dr. Perry Kendall, B.C.'s health officer, said he thinks members of the public will be left scratching their heads over the science and called the nurses' action "undermining."

This past August, Kendall announced the policy that requires health-care workers to get a flu shot or wear masks during the flu season. Union officials say those who are vaccinated are expected to wear a distinctive badge indicating they've had the shot.

"We're going to base our practice on the best science," said Debra McPherson, president of the nurses' union. "Getting an immunization, getting a foreign body shot into your body, should be a matter of choice.

"Certainly for health-care workers where the science is not compelling, it should continue to be their choice and they shouldn't be coerced or punished for choosing, based on their reading of the science, to not get it."

In the letter published in The Vancouver Sun, Dr. Tom Jefferson of the Cochrane Collaboration said Kendall misquoted a 2010 review conducted by his organization, when the health officer justified the vaccination of employees as a way to protect patients from the flu and pneumonia.

Jefferson said the Cochrane Collaboration drew no such conclusion.

"In other words, we report that no effect of the influenza vaccines was detectable on influenza and its complications such as death," he wrote.

He ended the letter with some strong words.

"It is not my place to judge the policies underway in British Columbia, but coercion and forcing public ridicule on human beings (for example by forcing them to wear distinctive badges or clothing) is usually the practice of tyrants," wrote Jefferson.

The union seized on the opinion and said in a release it "shredded" the rationale behind the policy.

McPherson said in a followup interview that her union has now corresponded with the CEO of Health Employers Association of BC and demanded it step back from the policy.

"If the science isn't there, how can the employer bring into place a coercive and punitive policy which has people wearing badges indicating whether or not they've been vaccinated for the flu," she said.

But Kendall pointed to several medical journals that he said promote similar policies.

"The Lancet, the British Medical Journal, the Canadian Medical Association Journal, the Society for Healthcare Epidemiology in the United States, they've all called for mandatory immunization of health-care workers," he said.

He said even though the vaccination isn't as effective as medical officials originally thought, it's still about 60 per cent effective, which considerably reduces the chances somebody will pick up the virus and pass it on to patients.

When asked how many patients die each year because they pick up viruses like the flu, Kendall said he didn't know because the information is not routinely collected.

He even acknowledged the public could be confused by the fight between the nurses and province.

"If I was a member of the public, I'd be scratching my head because it certainly seems very undermining," he said.

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