Quebec halts 1st doses of AstraZeneca vaccine, keeps future supply for 2nd only

Quebec's Health Ministry has decided to stop administering the AstraZeneca-Oxford vaccine as a first dose, effective immediately.

As a result, allappointments scheduled for today for a first dose ofAstraZenecahave been cancelled, and pharmacies are expected to contact the people affected by the sudden changetobook new appointments.

There have been concerns over the risk of rare but severe blood clots linked to AstraZeneca,and there are growing signs that the vaccine will not be prioritized in provincial and territorial rollouts across the country.

Recently,Ontario, Saskatchewan and Albertaalso paused the use of the vaccine for first doses.

In a statement issued Thursday, Quebec's Health Ministry maintained that the vaccine is safe, but said its decision to stop giving AstraZenecaas a first dose is based on new recommendationsfrom the province's immunization committee (CIQ).

The province's stock of AstraZenecavaccinesis nearly empty, but a shipment of 148,000 doses is expected next week.

The ministry said it is opting to set those doses aside for Quebecers who will want them as their second dose, after having received either the CoviShieldor AstraZeneca vaccines for their first dose.

Roughly half a million Quebecers have received an AstraZeneca shot.The province has offered the vaccine to people who are aged 45 and up.

"In fact, for the people who are 45 and older that have received the AstraZeneca vaccine as a first dose, the same vaccine is recommended for the second dose," the ministry's statement read.

People will have a choice, however, to opt for a Pfizer-BioNTech or Moderna vaccine for their second shot.

Early results from a U.K. study indicate that receiving different vaccines for a first and second dose can increase the chance of experiencing side effects such as fatigue, fever and headache.

The first round of results did not show the overall safety or effectiveness ofa mix-and-match approach.