BC is reporting almost double the rate of severe allergic reactions.

Toronto — As Canadian health officials assured the public that the pandemic H1N1 vaccine is as safe as the seasonal flu shot, at least one province is reporting almost double the rate of severe allergic reactions.

British Columbia Centre for Disease Control said it is probing why residents suffered anaphylaxis at a higher rate compared with the previous five seasonal-flu-vaccination programs, suggesting it could be because some people received H1N1 and the seasonal flu shot simultaneously.

It will be several more weeks before B.C. officials can definitively attribute the spike in the rate – 2.2 per 100,000 doses distributed, compared to 1.2 per 100,000 doses. None of the 18 anaphylaxis reactions in B.C. resulted in death.

“It would be fair to say that as more people are vaccinated in the weeks and months ahead, and more data are collected, the rates of adverse events per 100,000 may change both in B.C. and nationally,” said Roy Wadia, spokesman for the British Columbia Centre for Disease Control.

So far, no other province has reported higher rates of anaphylaxis – a severe, whole-body allergic reaction that can be characterized by respiratory distress, swelling of the lips, eyelids, throat or tongue, and low blood pressure, among other symptoms.

New Brunswick said it had one case of anaphylaxis in the 150,000 doses administered, while Manitoba, Alberta and Saskatchewan all reported rates of serious side effects that are comparable to previous years of providing seasonal flu shots. The Ontario health ministry said the province has had nine serious reactions but could not say how many of those were due to severe allergic reactions.

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