OTTAWA -- Canadian officials and doctors are defending sanctioning the mixing and matching of COVID-19 vaccines, after the World Health Organization鈥檚 (WHO) chief scientist issued a new caution about citizens opting to receive vaccines from different manufacturers, saying that the data remains limited on the practice.
On Monday, WHO Dr. Soumya Swaminathan said that the global health agency has received 鈥渁 lot of queries鈥 about people who have received a first dose of a COVID-19 vaccine from one pharmaceutical company and were planning to take another shot from a different authorized drug maker.
She called it: 鈥淎 little bit of a dangerous trend.鈥
The comment was made in the context of a conversation about booster doses, and CTVNews.ca has reached out for more clarity about the WHO鈥檚 position.
鈥淲e are in a data-free, evidence-free zone as far as mix and match. There is limited data on mix and match,鈥 she said, cautioning that it could become a 鈥渃haotic situation鈥 in countries where citizens decide to take 鈥渁 second, or a third, or a fourth dose.鈥
While this may cause concern among Canadians, who have been told that mixing vaccines is acceptable based on National Advisory Committee on Immunization (NACI) guidance, federal and provincial officials were quick to defend Canada鈥檚 approach and the health experts who suggested it, saying that all decisions are being made with peoples鈥 health and safety at the forefront.
鈥淚n terms of the dose regimens and the recommendations, those are decisions that are at the end of the day made by the provinces and territories who are responsible constitutionally for the administration of health care in their individual jurisdictions,鈥 said Procurement Minister Anita Anand. 鈥淔or our part, the federal government will continue to follow the science... as well as the guidance that鈥檚 coming out from other bodies.鈥
Anand also noted that she is among the numerous Canadians who have taken a mixed vaccine regime, having a first shot of Pfizer followed by a second dose of Moderna鈥檚 vaccine.
NACI ADVICE BASED ON PAST EXPERIENCE
Swaminathan noted that while there has been data on the efficacy of a first dose of AstraZeneca followed by a second dose of the Pfizer-BioNTech vaccine, there is limited data on the interchangeability of mRNA vaccines.
This was also noted by NACI when it updated its guidance, but the volunteer body said it made the recommendation based on the similarity of mRNA technology between Pfizer and Moderna.
鈥淎t this time, there is no reason to believe that mRNA vaccine series completion with a different authorized mRNA vaccine product would result in any additional safety issues or deficiency in protection," NACI said when it issued its guidance on mixing in early June.
Specifically, NACI鈥攚hich is separate and independent from Health Canada, who authorizes vaccines and therapies for use in this country鈥 have said that either Pfizer or Moderna was fine as a second shot for those who received AstraZeneca for their first.
The agency also said that while Canadians should be offered the same mRNA vaccine for their second as they received for their first if it鈥檚 available, a second shot of either Pfizer or Moderna was acceptable.
Asked about the WHO鈥檚 latest, Chief Medical Officer of Health for Nova Scotia Dr. Robert Strang said Monday that people should still take the first available dose offered.
鈥淲e have lots of available Moderna, lots of people had their first dose of Pfizer. The best thing they can do and it's very safe and effective, and NACI agrees with that, is to take the first appointment they can get,鈥 he said.
Manitoba鈥檚 Chief Provincial Public Health Officer Dr. Brent Roussin also backed up Canada鈥檚 approach as one that has worked in the past with other vaccines.
鈥淲e will always be looking at evidence as it comes out鈥 The evidence that we've seen to date is that the efficacy of mixing doses is the same鈥 the basic premise of interchangeability of vaccines is there,鈥 he said.
Swaminathan said that while, in time, mixing and matching vaccines may be found to be a 鈥渧ery good approach,鈥 the evidence is not there yet.
In an interview on 麻豆影视 Channel, ICU physician and associate professor of medicine at the University of Saskatchewan Dr. Hassan Masri questioned the WHO official鈥檚 messaging, saying that it wasn鈥檛 reflective of the more recent studies into mixing, didn鈥檛 take into account the historical scientific premise, and could lead to more vaccine hesitancy.
鈥淭here should be no scientific reason to have a problem with mixing and matching for example, Moderna and Pfizer, they're almost identical mRNA vaccines,鈥 he said. 鈥淭here should be no reason really to say that it's not appropriate, or that it's not safe.鈥
He also defended NACI鈥檚 decision to sign off on mixing in the name of seeing as many shots get in arms as quickly as possible.
鈥淲hat we see here in Canada, is that our numbers are coming down quite quickly,鈥 he said, referring to daily COVID-19 case counts.
CTVNews.ca has asked NACI for comment on the latest messaging from the WHO.
WHO CAUTIONS RUSHING BOOSTERS
Further, Swaminathan said that in some countries where vaccine supply is flush, people are 鈥渧oluntarily鈥 starting to think about taking an additional dose. This is something she warned against, both from a global vaccine supply perspective鈥攗sing up doses for third shots for some before others in developing nations have even had a first鈥攁s well as from a data perspective.
鈥淭here is no scientific evidence to suggest that boosters are definitely needed,鈥 she said. 鈥淲e have seen in some countries an increase in infections, but no significant increase in hospitalization or deaths. And it may well be that you need boosters after a year or two years, but at this point after six months of the primary dose, there doesn't seem to be any indication.鈥
This comes after Pfizer has signalled that a third dose of its COVID-19 vaccine may be beneficial after seeing indications of lessened immunity over time. While Israel is making plans to offer booster shots to high risk citizens, so far both U.S. and Canadian health officials are cautioning that it may be too soon to make that call.
Anand said Monday that while Pfizer has yet to ask Health Canada to consider authorizing a booster dose, for booster doses this year and in years following if they are required.
Swaminathan said that the WHO will make recommendations on boosters 鈥渨hen we think that they are needed鈥 and based on the data rather than on 鈥渋ndividual companies declaring that their vaccines should now be administered as a booster dose.鈥
Masri said that from his front-line perspective he agrees that pursuing booster doses should be better organized and not left up to individual citizens, and if that was the message the WHO was trying to get across, it could have been done more clearly.
鈥淭o come out and make such a broad statement that mixing and matching is dangerous, I think that announcement itself is dangerous.鈥
With files from CTVNews.ca's Brooklyn Neustaeter
