Tam says cancelled AstraZeneca update was not related to safety concerns

Tam says cancelled AstraZeneca update was not related to safety concerns

Canada's chief public health officer said today the National Advisory Committee on Immunization (NACI) recently postponed a planned update to its AstraZeneca guidance because it wanted to incorporate new data about COVID-19 variants — not because of any developments concerning the product's safety.

NACI was poised to provide an update on the AstraZeneca shot yesterday but the press conference was cancelled abruptly just minutes before it was due to start, leaving reporters with questions about the sudden scheduling change.

Dr. Theresa Tam said NACI, the committee of expert volunteers charged with reviewing vaccines, didn't call off the public appearance because of new safety issues or fears about the vaccine's potential side effects.

Only minutes before the update was cancelled Tuesday, New Brunswick officials reported one new case of the rare blood clots found in a very small number of AstraZeneca recipients.

In Canada, there have been just three reports of these clots in the brain post-vaccination — a phenomenon that also has been reported in Europe and the U.K. As of last Thursday, more than 700,000 of these shots have been administered here in this country.

WATCH: Chief Public Health Officer Dr. Theresa Tam on NACI's cancelled press conference

Tam said the NACI media update was rescheduled to give committee members a chance to review new data about the spread of so-called "variants of concern" during this third wave of the pandemic — and the impact they could have on the country's immunization campaign.

With caseloads mounting in some parts of the country, a number of public health experts have urged NACI and provincial decision makers to relax vaccine eligibility rules to get many more shots into the arms of younger Canadians to avoid more hospitalizations and death.

An AstraZeneca-Oxford COVID-19 vaccine vial.
An AstraZeneca-Oxford COVID-19 vaccine vial.(Jeff Stapleton/CBC)

"They thought it was pertinent in terms of analyzing the impact of COVID-19 on the population in light of the variants of concern, and not because of any changes in the data for the thrombosis disorder itself," she said, referring to vaccine-induced thrombocytopenia (VIPIT).

"That remains a rare disorder and the rates that they were looking at haven't changed," Tam said, adding that experts still believe VIPIT can develop in roughly 1 out of every 250,000 people who get an AstraZeneca shot.

After reviewing global data about VIPIT, Health Canada reaffirmed last week that the benefits of taking the AstraZeneca shot easily outweigh the risks. The regulator said the odds of developing any sort of blood clot are in 1 in 5 for people hospitalized with COVID-19.

Tam said VIPIT is not thought to be related to any underlying pre-existing conditions, or any physical or biological traits — it could occur in just about anyone.

While there have been reports of the condition developing in younger women, there is no hard evidence available to experts right now to suggest they are more susceptible than other groups, Tam said. One of the three people diagnosed with VIPIT in Canada so far is a man in his 50s, for example.

"The thrombotic syndrome with low platelets — it's a very specific underlying mechanism that is driving that rare event. There is no sex or age risk factors for that condition," she said.

Tam said the provinces that adjusted the AstraZeneca-related age restrictions over the weekend and into Monday did so after being briefed by NACI about any potential risks the product might pose to a younger demographic.

British Columbia, Alberta, Manitoba and Ontario are all now giving the AstraZeneca vaccine to people as young as 40, while Quebec has made it available to those 45 and older.

While Health Canada has approved the shot for use in all adults, NACI originally recommended the shots be reserved for adults over the age of 55. It was expected to formally make a change in guidance to allow younger people to get the shot at the now-cancelled press conference.

Tam said NACI would brief Canadians on this shot a later date.