Vaccine panel's call for longer dosage intervals is based on 'real-world' evidence, says health official

One of Canada's top public health officials sought to reassure Canadians today that a recommendation from a federal vaccine advisory committee to stretch out the time between COVID-19vaccine doses is a sound one.

Yesterday, theNational Advisory Committee on Immunization (NACI)recommended that the maximum interval between the first and second doses of all three COVID-19 vaccines approved for use in Canadashould increaseto four months due to limited supplies.

Deputy Chief Public Health Officer Dr. Howard Njoosaid the adviceis based on real-world data that shows doing so would lead to more people being protected from COVID-19 in a shorter time period.

"This recommendation is based on clinical trial reports and emerging real-world evidence from around the world. Datashows that several weeks after being administered, first doses of vaccines provide highly effective protection against symptomatic disease, hospitalization and death,"Njoo told a technical briefing today.

Confusion over conflictingadvice

Njoo'scomments appeared to be addressing theconfusion created by the fact that NACI's recommendation conflicts with those issued by Health Canada when it grantedregulatory approvals for the Pfizer-BioNTech, Modernaand AstraZeneca vaccines.

Regulatory documents provided byHealth Canadaupon approval of each vaccine state thatthe second dose of the Pfizer-BioNTech should be taken threeweeks after the first, the second Moderna shot should comefourweeks after the first, and the secondAstraZenecadose should be deliveredbetween fourand 12 weeks after the first. All of those recommendations are in line with the product monograph provided by the manufacturers.

Adding to the confusion, NACI recommended on Mondayagainst giving the AstraZeneca-Oxfordvaccine to people65 and older, although Health Canada has authorized it for usein adults of all ages.

But Njoo said the discrepancies can be explained bythe fact thatHealth Canada is a regulator and NACI is an advisorybody made up of medical experts.

"You have likely noticed that NACI's recommendations are sometimes different, possibly broader or narrower than the conditions of vaccine use that Health Canada has authorized. As the regulator, Health Canada authorizes each vaccine for use in Canada according to factors based on clinical trial evidence, whereas NACI bases its guidance on the available and evolving evidence in a real-world context, including the availability of other vaccines," Njoo said.

"What we expect is that NACI recommendations will complement not mirror those of Health Canada."

WATCH:Njoo comments on NACI recommendation to delay second COVID-19 vaccine doses

Njoo comments on NACI recommendation to delay second COVID-19 vaccine dose by up to four months in some jurisdictions

3 years ago

Duration 1:16

Deputy Chief Public Health Officer Dr. Howard Njoo comments on the National Advisory Committee of Immunization's recommendation that jurisdictions with limited supplies of COVID-19 vaccines delay administering second doses for up to four months.

The issue burst into the open on Monday when B.C.'sProvincial Health OfficerDr. Bonnie Henryannounced that the provincewould be extending the interval between doses of the Moderna, Pfizer and Oxford-AstraZeneca vaccinesto 16 weeks.

Some medicalexperts questioned that decision. Canada's chief science adviser, Mona Nemer,said doing so without proper clinical trials amounts to a"population level experiment."

Dr. Anthony Fauci, the top infectious disease expert in the U.S., told the Washington Post thatthe science doesn't support delaying a second dose for the Pfizer-BioNTech and Moderna vaccines. He said there isn't enoughevidence to determinehow much protection is provided by one dose of those vaccines, and how long it lasts.

Despite thosewarnings, several provinces followed Henry's leadand even more have indicated they intendto stretch the dosage interval.

While it appeared to some at the time that Henry was moving faster than the science, Njoosaid that NACI's experts briefed provincial medical officers of health over the weekend on the results of their analysis beforereleasing their recommendations publicly.

NACIconcluded that stretching the dosing interval to four months would allow up to 80 per cent of Canadians over the age of 16 to receive a single dose of COVID-19 vaccine by the end of June,without compromisingvaccine effectiveness.

"While studies have not yet collected four months of data on vaccine effectiveness after the first dose, the first two months of real world effectiveness are showing sustained high levels of protection," NACI said.

As for the AstraZeneca-Oxfordvaccine, Njoo saidit is safe and that evidence shows it provides protection against very serious disease and death in people of all ages. He said Health Canada has arigorous scientific review processand only approves vaccines that meet high standards forsafety, efficacy and quality.

Dr. Supriya Sharma, Health Canada's chief medical adviser, said expert advice will continue to change as more data becomes available from ongoing mass vaccination campaigns, and she urged provinces and territories to consider recommendations and evidence from both bodies when making decisions about their vaccine strategies.

"The messaging would be simpler if we had one set of data and we had one message and it never changed, but that's not what science does," said Sharma.

Decision on Johnson andJohnson imminent

At today's briefing, health officials also indicated that a regulatory decision on whether to approve Johnson & Johnson's COVID-19 vaccine is expected soon.

"The review of the Johnson & Johnsonsubmission is going very well, it's progressing, and we're expecting to have that completed anda decision in the next few days. I would say in the nextsevendays or so," said Sharma.

The company has said itsvaccine is66 per cent effective at preventing moderate to severe illness in a global clinical trial, and much more effective 85 per cent against the most serious symptoms. Canada has agreed to purchase up to38milliondoses if it is approved. The U.S. Food and Drug Administration approved it for use in that country last Saturday.

The approval of a fourth vaccinewould give a significant boost to Canada's vaccine rollout.Johnson and Johnson's vaccine is widely seen as one of theeasiest to administer because it requires only one dose and can be stored for long periods of time at regular refrigeratortemperatures.

Njoo said additional vaccines,coupled with the NACI recommendation on dosage intervals, could allow Canada tomeetthegoal of inoculatingall adultswho want a vaccine "several weeks" before the current target date of the end of September.

Maj.-Gen. Dany Fortin, the military commander leading Canada's COVID-19 vaccine logistics, said that while more vaccines would be good news,the current target remains the end of September.