By Kim Mackrael 

OTTAWA--A Canadian vaccine panel said Thursday that people who received a first dose of AstraZeneca PLC's vaccine against Covid-19 should get a different vaccine for their second dose.

Canada's national advisory panel on immunization said earlier this month that authorized Covid-19 vaccines could be mixed, and noted some people might prefer to get a messenger RNA vaccine for their second shot. The panel has previously said mRNA vaccines, such as the ones produced by Pfizer Inc. in partnership with BioNTech SE, as well as Moderna Inc., are preferable to viral vector vaccines, such as those developed by AstraZeneca and Johnson & Johnson.

On Thursday, it changed its advice to recommend against the use of AstraZeneca's vaccine in most cases.

"An mRNA vaccine should now be offered as the second dose for individuals who received a first dose" of AstraZeneca's vaccine, said Dr. Howard Njoo, Canada's deputy chief public health officer. People who are getting their first vaccine dose should also be offered an mRNA vaccine unless they have a contraindication or none of those vaccines are available, he said.

Dr. Njoo said the advisory panel's advice is based on emerging evidence that shows a potentially better immune response from a mixed vaccine schedule, and concerns about blood clotting associated with the AstraZeneca vaccine. Another factor the advisory panel considered is the increased availability of mRNA vaccines in Canada, he said.

The panel's recommendations aren't binding, but tend to be followed by provinces in Canada, which are responsible for delivering health care.

After a sluggish start earlier in the year, Canada has sharply increased its administration of Covid-19 vaccines in recent months. Nearly 66% of the population had received at least one dose of a Covid-19 vaccine as of June 16, although just 15% of the population is fully vaccinated.


Write to Kim Mackrael at


(END) Dow Jones Newswires

June 17, 2021 18:05 ET (22:05 GMT)

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