(CP /Halifax Chronicle Herald-Tim Krochak) Renee Hammond, 12, of Tantallon, N.S., reacts to the prick of a needle during her flu shot. (CP /Halifax Chronicle Herald-Tim Krochak)

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TORONTO (CP) - Most people who reacted badly to a flu shot two years ago don't need to avoid getting one in the future, suggests a study from researchers in British Columbia and Quebec. The study, which was fast-tracked by the Canadian Medical Association Journal, found that individuals who had suffered from what has since been dubbed oculorespiratory syndrome after having the 2000 flu shot were no more likely than anyone else to have an adverse reaction when they got their flu shot the following year.

"We know that it's not an intrinsic problem for those who had it, that they need not worry that every time they get the flu vaccine it's going to recur," lead author Dr. Danuta Skowronski said Monday from Vancouver.

"So people who had ORS before can feel confident in getting immunized again. And their caretakers should feel confident in recommending it."

Less than five per cent of people suffered a recurrence in 2001 and those who did experienced milder symptoms than in 2000, added Skowronski, a physician epidemiologist with the University of British Columbia's Centre for Disease Control.

Every year, a small number of people complain of side-effects after getting a flu shot, with tenderness at the injection site a common complaint.

But in 2000 there was an unusually high number of adverse reactions reported - 2,450. And about 70 per cent of them were for eye or respiratory problems - the red, runny eyes and wheezing-type symptoms normally associated with an allergic reaction.

Forty per cent of the total were classified as being severe enough to be characterized as oculorespiratory syndrome.

Since allergic reactions can worsen with repeated exposure to the triggering agent, public health officials worried that perhaps these individuals should not get flu shots in the future.

They conducted a trial on some of these people in preparation for last year's flu shot program, giving some a placebo and some a flu shot and monitoring the results. The trial was stopped early - after only 65 of a planned 150 participants had been treated - when it appeared that the reaction rate was reaching unacceptably high levels.

Based on that trial, the federal government's Advisory Committee on Immunization warned that people who had experienced an adverse reaction in 2000 should be cautious about getting future flu shots and should first weigh the pros and cons with their doctors.

Skowronski - who was involved in that trial as well - said that while it had to be stopped on ethical grounds, researchers recognized that many of the reactions they saw were minor. She felt that if they had been able to ask participants whether the reaction they experienced in 2001 would deter them from getting a flu shot in future, the answer would likely have been "No."

So her group set out to see what had happened to people outside the study who had decided to get a flu shot last winter, despite having experienced an adverse reaction the year before. A phone survey located 122 people who reported suffering oculorespiratory syndrome in 2000 but who nonetheless got a flu shot in 2001.

Their experiences are the basis of these findings, which proponents of flu shots herald as good news.

"This is not the influenza vaccine doing this. This is the manufacturing of the influenza vaccine that resulted in this," said Dr. Donald Low, an infectious disease expert at Mount Sinai Hospital in Toronto.

"And I think that's reassuring to think that was what it was."

Health Canada has subsequently worked with vaccine manufacturers to pinpoint and resolve the problem.

Skowronski noted the results cannot be generalized to include people who suffered severe reactions - requiring hospitalization - in 2000. There were too few of them to start out with and very few of them were willing to get a flu shot in 2001.

For those individuals, authorities continue to advise caution, she said.