B.C. nurses are seizing on the work of a UK-based health science organization that questions the scientific evidence for forcing health workers to get flu shots.

In August, provincial health officer Dr. Perry Kendall announced the policy that requires health-care workers to get a flu shot or wear masks during the flu season.

But the B.C. Nurses' Union took issue with the policy almost immediately and said the government should educate health-care workers on the benefits of vaccines but keep those vaccines voluntary.

The nurses stepped up their fight Wednesday by citing a letter in a Vancouver daily newspaper written by a doctor associated with the Cochrane Collaboration.

The nurses say the respected group has "shredded" the credibility of the reasons Kendall put forward to justify the policy and the nurses have launched a grievance over the issue.

But Kendall says 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.