Another dose of AstraZeneca still an option in Quebec, but mRNA vaccine deemed 'preferable'

The National Advisory Committee on Immunization is going further than Quebec, recommending provinces should stop administering AstraZeneca-Oxford vaccine as a booster altogether.

Quebec appeared to take that stronger stance on Wednesday, but then walked it back this morning.

Health Minister Christian Dub told reporters earlier today there wasan "error of communication," after anoticeon the province's website appeared to signala significant change in the province's vaccination strategy.

The postWednesdaystated thatpeople who received the AstraZeneca vaccine as a first dose shouldswitch to an mRNA vaccine either Pfizer-BioNTech or Moderna for their second dose.

This raised questions, given that the province has been administering AstraZeneca as a second dosefor nearly three weeks. On Thursday, Dubapologized and said the wordingwas inaccurate.

"There was a statement yesterday that was wrong. People that have received AstraZeneca [as a first dose] should not necessarily take an mRNA [vaccine as a second dose," Dub said at a news conference.

"There was a mistake."

The message on the government's website has since been modified. Itnow says that people who received AstraZeneca for their first dose "could receive" anmRNA vaccine and it "appears preferable" to do so,based on a review of research by Quebec's immunization committee (CIQ).

Dub said people who received a dose ofAstraZeneca still have the option of receivinga second dose of the same, or receiving Pfizer or Moderna.

What the advisory panels say

For its part, the CIQ recommendspeople aged 45 and up who received AstraZeneca for their first doseopt for Pfizer or Modernafor their second one, citingrecent data that suggestsdoing so will provide stronger protection against COVID-19.

But the CIQ also states that choosing a second dose of AstraZeneca is still an option.

The National Advisory Committee on Immunization (NACI) went further Thursday. Itrecommendedprovinces stop administering the AstraZeneca as booster shots for people whoalready received first doses of the product.

"An mRNA vaccine is now preferred as the second dose for individuals who received a first dose of the AstraZeneca/COVISHIELD vaccine, based on emerging evidence of a potentially better immune response from this mixed vaccine schedule," NACI said in a statement released today.

Since early May, all provinces have halted the use of AstraZeneca for first doses. Many havecontinued using forbooster shots.

Dr.Matthew Oughton, an infectious diseases specialist at Montreal's Jewish General Hospital, said earlyresearch suggests mixing doses is effective.

"When the first dose is AstraZeneca and the [booster] is Pfizer or Moderna, there have been a lot of hints that that will probably give you the best overall immune response," Oughton said.

Ultimately, an individual's decision in Quebec may come down to supply.

Quebec is running out of AstraZeneca doses and it's not clear when the next batch will arrive, while more Pfizer and Moderna is set to arrive in the coming weeks.