The National Advisory Committee on Immunization (NACI) recommends that the AstraZeneca COVID-19 not be used for people under the age of 55 in Canada, following concerns around blood clots associated with low levels of platelets, vaccine-induced prothrombotic immune thrombocytopenia (VIPIT).
This applies to both the AstraZeneca COVID-19 vaccine and COVISHIELD from Serum Institute of India.
NACI indicates that cases have primarily been in women under the age of 55, although cases in men have been reported as well, and mostly occurring between four and 16 days after receipt of the vaccine.
"The exact mechanism by which the AstraZeneca vaccine triggered VIPIT is still under investigation and no other risk factors have been consistently identified in patients who develop VIPIT," Dr. Shelley Deeks, vice-chair of NACI, said at a briefing on Monday. "This adverse event has not been identified [with] mRNA COVID-19 vaccines to date."
The rate of this adverse event has not been confirmed but based on information from the European Medicines Agency from March 18, it is estimated that about one in one million people vaccinated with the AstraZeneca vaccine experienced VIPIT. That being said, a higher rate of one in 100,000 people who received the vaccine was reported by the Paul-Ehrlich Institut in Germany.
The observed fatality rate of VIPIT cases is about 40 per cent, but Dr. Deeks said the likelihood of fatality may decrease with "increase awareness" of VIPIT and early treatment.
The AstraZeneca vaccine may still be offered to older individuals in Canada, with informed consent, given the "increased risk of severe COVID-19 disease in this population and as VIPIT appears to be rarer in that age group," Dr. Deeks confirmed.
Possible symptoms include:
Shortness of breath
Persistent abdominal pain
Sudden onset of severe or persistent worsening headaches or blurred vision
Skin bruising, other than the site of vaccination
Anyone who begins to see these symptoms, starting four days or more after vaccination, should seek immediate medical attention.
For people who are concerned about getting their second dose of the AstraZeneca vaccine, decisions on the type of second dose that will be offered to those who have received the first AstraZeneca shot will be determined on "the latest evidence and research," Dr. Howard Njoo, Canada's deputy chief public health officer said.
While no VIPIT cases have been identified domestically, Health Canada will require the manufacturers conduct a "detailed assessment of the benefits and risks of the vaccine by age and sex in the Canadian context."
"This information will support the ongoing evaluation of these rare blood clotting events, and allow Health Canada to determine if there are specific groups of people who may be at higher risk," the information from Health Canada reads.
Dr. Supriya Sharma, a senior medical advisor with Health Canada, said this recommendation is being made based on the risk of someone in the younger age group having a severe outcome to COVID-19 versus the risks associated with VIPIT.
At a briefing on Monday, Dr. Caroline Quach-Thanh, chair of NACI, did indicate that this vaccine "has had all the ups and downs, it looks like a rollercoaster," but also stressed that recommendations are changing based on evolving information.
Prince Edward Island was the first province to confirm Monday that it is pausing the administration of the AstraZeneca COVID-19 vaccine.
"For those Islanders who have been vaccinated to date using AstraZeneca, 1,680 of them, I understand this news would be a little bit disturbing [to hear] but I do want to reiterate...that the risk of developing a serious problem after being immunized is very, very low," P.E.I. premier Dennis King said at a press conference on Monday.
At a press conference on Monday, Ontario Premier Doug Ford said he "won't hesitate" to stop the use of the AstraZeneca vaccine "if it's going to put anyone in harm."
"I’d rather wait...a month or two months for Pfizer and Moderna and J&J [Johnson & Johnson] than roll the dice on this AstraZeneca," Ford said.
He did go on to confirm that people who have received the AstraZeneca vaccine did not "roll the dice" but stressed that his comment is specific to the younger age group.
Ontario's Deputy Premier and Minister of Health, Christine Elliott, received her first dose of the AstraZeneca vaccine on Monday morning.