While the outbreak, dubbed oculo-respiratory syndrome, is well under control -- resulting in only four hospitalizations and no deaths -- it has set off alarm bells among public-health experts, who worry about the country's ability to respond to a genuine crisis.

"Safety, and the perception of safety, is key to our immunization programs," Dr. Greg Hammond, director of public health for Manitoba Health, said yesterday at a conference in Halifax.

But the syndrome has highlighted some glaring shortcomings in Canada's vaccination infrastructure, he told more than 800 delegates attending the Fourth National Immunization Conference.

The most troubling is an absence of immunization registries. This means public-health officials do not know how many doses of the flu vaccine have been administered.

The lack of bar-code numbering on the products means it would also be impossible to trace individuals if there turned out to be a serious problem with a vaccine, Dr. Hammond said. (More than 20 million vaccine doses are administered annually in Canada, making vaccination the most frequent medical act.)

In addition, a lack of communications strategy means public-health officials would not be ready to issue timely warnings, and the lack of research money means it has been a strain to get experts to turn their attention to this issue, he said.

"This is serious stuff. We must get it right," he told delegates.

Oculo-respiratory syndrome is characterized by conjunctivitis (red eyes), respiratory symptoms (cough, sore throat or wheezing) and occasionally a facial rash that occurs in the hours after inoculation with the flu vaccine. The symptoms clear up within 48 hours.

Dr. Eleni Galanis of Health Canada said that 921 cases have been identified since October. Last year, 12 people receiving the flu vaccine reported respiratory problems. (Another striking contrast is that the United States has recorded 200 cases of this sort of reaction in the past decade.)

More than half the cases of oculo-respiratory syndrome (472) were in Quebec, and virtually all of the reactions (911) have been in people receiving Fluviral, a vaccine manufactured by BioChem Pharma Inc. of Laval, Que. The company has shipped 3.8 million doses of the product, largely in Quebec and British Columbia.

Another manufacturer, Aventis Pasteur Inc. of Toronto, has shipped 5.6 million doses of two other flu vaccines but the two account for only 10 cases of oculo-respiratory syndrome.

Researchers are not certain, however, whether the reaction might affect how well the vaccine works.