Deputy chief public health officer Dr. Howard Njoo responds to a question during a news conference, Tuesday, Jan. 12, 2021 in Ottawa. THE CANADIAN PRESS/Adrian Wyld

Deputy chief public health officer Dr. Howard Njoo responds to a question during a news conference, Tuesday, Jan. 12, 2021 in Ottawa. THE CANADIAN PRESS/Adrian Wyld

UPDATE: Data suggests Pfizer vaccine may be almost as good after 1 dose as 2

Pfizer to ship nearly three million doses over next six weeks, Moderna more than 1.4 million.

There is compelling evidence that a single dose of COVID-19 vaccines may provide almost as much protection as giving two doses, Canada’s deputy chief public health officer said Thursday.

Dr. Howard Njoo said the advisory committee of federal and provincial public health officers is having an active discussion about whether Canada would be better served to delay the second doses of vaccines in a bid to give protection to more vulnerable people quicker.

“These are what I would call early data in terms of a vaccine effectiveness or studies,” he said. “And the indications are that there’s a good level of protection after just one dose.”

Canada intends to vaccinate three million people with two doses by the end of March.

More than 990,000 Canadians have received at least one dose, and about one-third of those have also received their second doses.

RELATED: Senior homes stay safe as B.C. finds 427 more cases of COVID-19

RELATED: Two young adults from Cowichan Tribes have died of COVID-19

Quebec’s immunization committee went as far Thursday as to recommend nobody get a second dose until a first dose is injected into everyone in six high-risk groups, including people over 70, health-care workers, and people who live in long-term care homes and retirement residences.

The committee reported that single doses have been 80 per cent effective at preventing COVID-19 so far among long-term care residents and health workers who were vaccinated.

Questions about delaying the second doses arose almost as soon as vaccinations began in December, prompting a whirlwind of debate among scientists about the ethics of “going off label.”

Pfizer-BioNTech and Moderna’s vaccines — the two currently authorized in Canada — were tested by giving two doses, 21 days and 28 days apart respectively.

But Dr. Danuta Skowronski, the epidemiology lead for influenza and emerging respiratory pathogens at the British Columbia Centre for Disease Control, said data show two weeks after one dose of either vaccine, the protection against COVID-19 was almost as good as what was found after two doses.

Skowronski and Dr. Dr. Gaston De Serres from the Institut national de santé publique du Québec made the case in a letter published in the New England Journal of Medicine this week.

Moderna reported itself that two weeks after one dose, those who got the vaccine were 92 per cent less likely to develop COVID-19 symptoms.

Pfizer and BioNTech, whose vaccine uses similar genetic technology to Moderna’s, said their vaccine was 52 per cent effective after one dose, but 94.5 per cent effective after two.

Skowronski said Pfizer started measuring illness as soon as the injections were given, which she said is “unreasonable.”

“It’s basic vaccinology that you don’t expect the vaccine to activate the immune system instantaneously,” she said, in an interview with The Canadian Press.

Skowronski said if you wait two weeks to start counting infections, there were 92 per cent fewer infections of COVID-19 among those who got one dose of the vaccine, compared with those who got the placebo.

At that level of protection, she said “we need to get a first dose into our priority populations, and the most vulnerable of those at greatest risk of severe outcomes and the precious resource of our front-line health-care workers.”

She said the second dose should eventually be given but said there isn’t a maximum time she would put on how long to wait.

Pfizer has issued caution about adjusting the dosing schedule but said the decision to do so rests with local authorities.

“We at Pfizer believe that it is critical for health authorities to carry on surveillance on implemented alternative dosing schedules to ensure that vaccines provide the maximum possible protection,” the company’s statement reads.

Canada’s National Advisory Committee on Immunization said in January that the recommended schedule should be followed wherever possible but that delaying a second dose up to six weeks could be beneficial, particularly with a shortage of supplies and a fast-spreading virus.

Skowronski said waiting six weeks instead of three or four for a second dose won’t do much.

“That’s not maximizing coverage that we need to undertake with the scarcity of the vaccine that is available now.”

Several provinces have been delaying the second doses a couple of weeks, particularly as deliveries of both Pfizer-BioNTech’s vaccine and Moderna’s slowed to a crawl in mid-January.

Those delays appear to be over. Pfizer says it will ship nearly three million doses over the next six weeks, and Moderna promises to ship more than 1.4 million.

With the two authorized vaccines, and the two-dose schedule followed, Canada expects to vaccinate 14.5 million people by the end of June and all Canadians who want to be immunized by the end of September.

A new vaccination schedule issued Thursday shows if the other three vaccines currently being reviewed get approved by Health Canada, 24.5 million Canadians could be vaccinated before Canada Day.

Mia Rabson, The Canadian Press

Like us on Facebook and follow us on Twitter.

Want to support local journalism? Make a donation here.

Coronavirus

Get local stories you won't find anywhere else right to your inbox.
Sign up here

Just Posted

School District 27 (SD27) issued notice Thursday, Feb. 25 of a COVID-19 exposure at Mountview Elementary School. (Angie Mindus photo)
School district reports positive COVID-19 case in Williams Lake elementary school

A letter went home to families of Mountview Elementary School

The City of Williams Lake is asking for public feedback on whether it should explore the opportunity to host a Greater Metro Hockey League team in Williams Lake. (Angie Mindus photo - Williams Lake Tribune)
City of Williams Lake seeks feedback on hosting junior hockey league team

A league expansion application in Quesnel is also pending

A rainbow shining on Kelowna General Hospital on May 12, 2020 International Nurses Day. (Steve Wensley - Prime Light Media)
New COVID cases trending down in Interior Health

24 new cases reported Thursday, Feb. 25, death at Kelowna General Hospital

LADDER USED IN FIRE FIGHT: While smoke billows out of the second floor of the Maple Leaf Hotel, members of the Williams Lake Volunteer Fire Department fight to contain the blaze. The department was called out Tuesday morning to battle the blaze that wreaked havoc on the interior of the 57-year-old hotel. One man, Harold Hurst of Riske Creek, died in the fire. (Ernest Engemoen photo - Williams Lake Tribune, April 12, 1977)
FROM OUR ARCHIVES: Ladder used in fire fight

The department was called out Tuesday morning to battle the blaze

Provincial funding in the amount of $300,000 has been announced for the Cariboo Regional District’s plans to improve the Anahim Lake Airport runway. (CRD photo)
$300,000 provincial funding to fuel Anahim Lake Airport runway upgrade

The recovery grant is one of 38 announced to support jobs in rural communities

Provincial health officer Dr. Bonnie Henry updates B.C.’s COVID-19 situation at the B.C. legislature. (B.C. government)
B.C. reports 10 additional deaths, 395 new COVID-19 cases

The majority of new coronavirus infections were in the Fraser Health region

Cannabis bought in British Columbia (Ashley Wadhwani/Black Press Media)
Is it time to start thinking about greener ways to package cannabis?

Packaging suppliers are still figuring eco-friendly and affordable packaging options that fit the mandates of Cannabis Regulations

A new survey has found that virtual visits are British Columbian’s preferred way to see the doctor amid the COVID-19 pandemic. (Unsplash)
Majority of British Columbians now prefer routine virtual doctor’s visits: study

More than 82% feel virtual health options reduce wait times, 64% think they lead to better health

Captain and Maria, a pair of big and affectionate akbash dogs, must be adopted together because they are so closely bonded. (SPCA image)
Shuswap SPCA seeks forever home for inseparable Akbash dogs

A fundraiser to help medical expenses for Captain and Maria earned over 10 times its goal

The missing camper heard a GSAR helicopter, and ran from his tree well waving his arms. File photo
Man trapped on Manning mountain did nearly everything right to survive: SAR

The winter experienced camper was overwhelmed by snow conditions

Cory Mills, Eric Blackmore and A.J. Jensen, all 20, drown in the Sooke River in February 2020. (Contributed photos)
Coroner confirms ‘puddle jumping’ in 2020 drowning deaths of 3 B.C. men

Cory Mills, Eric Blackmore and A.J. Jensen pulled into raging river driving through nearby flooding

Castlegar doctor Megan Taylor contracted COVID-19 in November. This photo was taken before the pandemic. Photo: Submitted
Kootenay doctor shares experience contracting COVID-19

Castlegar doctor shares her COVID experience

Ashley Paxman, 29, is in the ICU after being struck by a vehicle along Highway 97 Feb. 18, 2021. She remains in critical condition. (GoFundMe)
Okanagan woman in ICU with broken bones in face after being struck by car

She remains in serious condition following Feb. 18 incident

The booklet roots present day activism in the history of racist policies, arguing the history must be acknowledged in order to change. (CCPA)
New resource dives into 150 years of racist policy in B.C.

Racist history must be acknowledged in order to change, authors say

Most Read