During the 2000–2001 influenza immunization campaign, a newly identified oculo-respiratory syndrome (ORS) emerged in Canada as an adverse effect associated with one manufacturer’s influenza vaccine. This signal was detected within days of starting the immunization campaign—a credit to the sensitivity of vaccine adverse event surveillance in Canada. In part, rapid notification was related to the fact that health care workers were the first to be immunized.
The original case definition for ORS specified bilateral conjunctivitis, facial edema, or respiratory symptoms beginning 2–24hrs after influenza vaccination and resolving within 48 hrs after onset. Within days after the start of the 2000–2001 vaccination campaign, the British Columbia Centre for Disease Control (BCCDC) received reports of bilateral red eyes, conjunctivitis, and respiratory symptoms that occurred within a few hours after influenza vaccination. Most, but not all, reports came from health care workers who were vaccinated early, during an expanded campaign to protect health care providers.
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Shortly thereafter, similar reports were received from different regions across the province and involving other targeted groups. Notification to Health Canada (Ottawa, Ontario) and national discussion confirmed that this syndrome was occurring in a number of provinces in association with one influenza vaccine. National enhanced surveillance and special investigations were developed to assess this association.
In all, 2450 adverse events associated with the influenza vaccine were reported nationally in 2000–2001: 1735 individuals reported ocular or respiratory symptoms and 960 met the 2000–2001 ORS case definition. Ninety-six percent (925) of the 960 ORS cases were linked to one Canadian manufacturer’s vaccine (Fluviral S/F produced by Shire Biologics).
The risk of ORS was greater for women, individuals aged 40–59 years and those vaccinated for the first time against influenza in 2000.
On the basis of cases that emerged early in the vaccination campaign,“oculo-respiratory syndrome” (ORS) was defined in 2000 as bilateral red eyes or respiratory symptoms (including 1 or more of the following respiratory symptoms: cough, wheeze, chest tightness, difficulty breathing, difficulty swallowing, hoarseness or sore throat) or facial edema beginning 2–24 hrs after influenza vaccination and resolving less than 48 hrs after onset.
It was observed for the next 4 years and ORS was reported during four consecutive seasons 2000, 2001, 2002 and 2003 in the province of Quebec, Canada.
During the 4 years, incidence was highest in people aged 40-59 years and declined in older age groups. The clinical profile of ORS has remained remarkably stable over years. Overall, ocular, respiratory symptoms or facial edema were reported by 58%, 84% and 31% of patients, respectively, and 15% had symptoms including all three symptom categories. ORS lasted more than a week in 8-13% of the cases
ORS is not a true allergic reaction. However, because many signs and symptoms of ORS are similar to those observed during an allergic reaction, it is often difficult to distinguish between ORS and an allergic reaction.
ORS is an adverse event that occurred with both influenza vaccines used in Canada. Its frequency has declined substantially but is still present after 4 years. It constitutes a clinical entity distinct from anaphylactic allergy. Unlike anaphylaxis, ORS does not constitute an absolute contraindication to further doses.
