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Health Unit: No reports of blood clotting condition from AstraZeneca in district

According to the Ontario Science Table, the rare blood clotting condition seems to occur between four and 28 days post-vaccination
2021 04 07 North Bay Parry Sound District Health Unit (Campaigne)
The Oak Street West offices of the North Bay Parry Sound District Health Unit.

Recipients in the Nipissing–Parry Sound district have thus far avoided the blood clotting condition linked to the Oxford-AstraZeneca COVID-19 vaccine, according to the local Health Unit.

"There have been 3,368 doses of AstraZeneca administered within our district and there have been four Adverse Events Following Immunization (AEFIs) in individuals who have received that vaccine,"  the North Bay Parry Sound District Health Unit tells BayToday. "None of the adverse events were Vaccine-Induced Immune Thrombotic Thrombocytopenia (VITT)."

According to the Ontario Science Table, "VITT seems to occur between 4 and 28 days post-vaccination. Symptoms that begin in this time frame should raise the clinical suspicion of VITT."

The Health Unit says it is important to note that AEFIs are not necessarily caused by the vaccine. "They are conditions that are monitored to see if they happen more commonly after immunization."

"On Tuesday, the Ministry of Health announced a pause on the rollout and administration of first doses of the AstraZeneca vaccine," said Andrea McLellan, the Health Unit's Director of COVID-19 Immunization Strategy. "At this time, we are awaiting direction from the Ministry of Health with respect to the second dose for those individuals who have already received their first dose of AstraZeneca vaccine."

See related: Ontario pauses AstraZeneca delivery because of blood clot link

Dr. David Williams, Ontario’s Chief Medical Officer of Health stated Tuesday the decision was made "out of an abundance of caution due to an observed increase in the rare blood clotting condition," associated with the AstraZeneca vaccine. 

As of May 8, 651,012 doses of the AstraZeneca vaccine were administered with a rate of Vaccine-induced immune thrombotic thrombocytopenia (VITT) of 0.9 per 100,000 doses. Williams advised recent reports prior to the pause with a rate of 1.7 per 100,000 doses administered led to the decision.

AstraZeneca has been distributed in accordance with the recommendations and guidelines from Health Canada and the Ministry of Health. Select pharmacies across the province lowered the booking age for eligible people ages 40 or older in 2021, in mid-April. 

See also: Health Unit comments on AstraZeneca vaccine now available to Ontarians 40 and up

Following the Ministry of Health’s guidance, the Health Unit's "strong recommendation," at the time was to "get the first COVID-19 vaccine available to you."

On April 13, the first instance of the blood clotting condition was reported in Canada. Of 2.3 million-plus doses of AstraZeneca administered in Canada, to date, 28 suspected cases of the rare condition VITT have been identified. Four have died in cases related to VITT.

In light of concerns about side effects related to the AstraZeneca vaccine, the North Bay Parry Sound District Health Unit advised on April 20, "Although studies in Europe have indicated a risk of blood clots when receiving the AstraZeneca vaccine, the risk of serious complications linked to COVID-19 is greater than the risk associated with receiving the AstraZeneca vaccine."

On April 23, the first Ontario case was reported.

Dr. Williams noted Tuesday increased and more reliable supply of the Pfizer and Moderna mRNA vaccines and the downward trend in cases contributed to the decision to pause AstraZeneca doses. Additional details on second dose recommendations will be shared following further scientific review.

See also: Questions remain about the future of the Oxford-AstraZeneca shot in Canada

And: Ontario to get new AstraZeneca shipment, reserve doses for second shots

"We are also seeing early promising results of administering two doses of different vaccines and have asked the National Advisory Committee on Immunization (NACI) to provide direction on the interchangeability of COVID-19 vaccines," said Williams.

Summing up his remarks, Williams added, "Based on the much higher risks of COVID-19 infection recently observed in Ontario including hospitalization, serious illness and death, we maintain that those who received their first dose with the AstraZeneca vaccine did absolutely the right thing to prevent illness, and to protect their families, loved ones and communities."