THE CANADIAN PRESS/Darryl Dyck

THE CANADIAN PRESS/Darryl Dyck

NACI doubles down on 4-month gap, says 75% of Canadians could get COVID jab by mid-June

Committee says 75% of Canadians can be vaccinated by mid-June

The National Advisory Committee on Immunization has doubled down on its recommendation of a four-month gap between doses of COVID-19 vaccines in an update released Wednesday (April 7).

In the update, NACI said that delaying the second dose until everyone has received their first dose would allow 75 per cent of Canadians to get it by mid-June.

“Second doses should be offered as soon as possible after all eligible populations have been offered first doses, with priority given to those at highest risk of severe illness and death from COVID-19 disease,” NACI said. “With Canada’s expected vaccine supply, the interval between the first and second dose is expected to be less than four months.”

NACI said that provinces could choose to shorten the time between doses in certain populations based on local cases, vaccine supply and new evidence. The committee first made the four-month gap recommendation in March, citing vaccine availability.

Evidence for delaying the second dose came from a variety of real life scenarios, both in Canada and abroad, although NACI said many of the studies had not yet been peer reviewed.

“Effectiveness data from Canada and the UK demonstrates protection from the mRNA vaccines based on analyses extending to about 8 weeks from vaccination,” NACI said.

“Experience with other multi-dose vaccines after a single dose suggests protection could last for six months or longer in adolescents and adults (e.g., hepatitis A and human papillomavirus vaccines).”

NACI said that as a “general vaccination principle,” interrupting an immunization schedule doesn’t require redoing the first dose.

“Furthermore, a longer interval between the priming and boosting doses allows maturation of the memory B cells, resulting in a higher and more durable response.”

NACI said that current evidence shows 92 per cent efficacy for the Pfizer and Moderna mRNA vaccines and 76% efficacy for the AstraZeneca viral vector vaccine.

“Effectiveness has been documented for up to two months after the first dose of the mRNA vaccines, and the AstraZeneca clinical trial publication modelled one-dose efficacy up to 90 days after vaccination,” NACI said.

Data from long-term care residents in B.C. showed vaccine effectiveness of 87 per cent between 21 and 54 days after the first dose, while other data provided by the B.C. Centre for Disease Control showed effectiveness of 80 per cent from 21 to 43 days after the first dose in long-term care residents. Similar immunization intervals in health-care workers showed similar results.

NACI said that data from the AstraZeneca clinical trial showed maximum efficacy when the interval between doses was extended to over 12 weeks. Efficacy at less than six weeks after the first dose was at about 55 per cent, while efficacy 12 weeks after the first dose was at 81 per cent.

B.C. has used Pfizer, and to a less extent Moderna, in its age-based vaccination program, as well as for health-care workers. AstraZeneca was initially being used for frontline workers, but after concerns over effectiveness in older adults and blood clots in younger people, B.C. moved to using it to vaccinate 55 to 65 year old via community pharmacies.


@katslepian

katya.slepian@bpdigital.ca

Like us on Facebook and follow us on Twitter.

Want to support local journalism during the pandemic? Make a donation here.

Coronavirus

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

Just Posted

The Millstone River in Nanaimo. (News Bulletin file photo)
Regional district looks at value of Nanaimo’s natural assets

Report focused on the Millstone River could inform future decisions on corporate asset management

Protesters gather along the Pearson Bridge on Terminal Avenue in downtown Nanaimo last month as part of an event called Worth More Standing. (News Bulletin file photo)
LETTER TO THE EDITOR: B.C. hasn’t managed forests properly

Protesters opposing logging in Fairy Creek speak for many British Columbians, say letter writers

Nanaimo singer Victoria Vaughn recently released an EP with local producer Austin Penner. (Photo courtesy Taylor Murray)
Nanaimo singer and recent VIU grad releases EP about becoming an adult

Victoria Vaughn’s ‘Growing Pains’ recorded with local producer Austin Penner

The B.C. Centre for Disease Control has listed Harbour Air and Air Canada flights to and from Nanaimo, from April 3, 4 and 12, on its list of flights with COVID-19. (News Bulletin file)
COVID-19 cases reported for Air Canada, Harbour Air flights, says disease control centre

Nanaimo flights for April 3, 4 and 12 listed on BCCDC’s list of flights with COVID-19

Rebates through Clean B.C.’s Better Homes New Construction program are available, says the City of Nanaimo. (Vancouver Island University photo)
Energy-efficient home builds in Nanaimo eligible for up to $15K in rebates

All building permits issued on, or after, April 1, 2020 eligible, says City of Nanaimo

Pat Kauwell, a semi-retired construction manager, lives in his fifth-wheel trailer on Maxey Road because that’s what he can afford on his pension, but a Regional District of Nanaimo bylaw prohibits using RVs as permanent dwellings, leaving Kauwell and others like him with few affordable housing options. (Chris Bush/News Bulletin)
Housing crunch or not, it’s illegal to live in an RV in Nanaimo

Regional District of Nanaimo bylaw forcing pensioner to move RV he calls home off private farm land

Deputy Prime Minister and Minister of Finance Chrystia Freeland responds to a question during Question Period in the House of Commons Tuesday December 8, 2020 in Ottawa. The stage is set for arguably the most important federal budget in recent memory, as the Liberal government prepares to unveil its plan for Canada’s post-pandemic recovery even as a third wave of COVID-19 rages across the country. THE CANADIAN PRESS/Adrian Wyld
Election reticence expected to temper political battle over federal budget

Opposition parties have laid out their own demands in the weeks leading up to the budget

Noel Brown, Snuneymuxw First Nation carver, observes the house post he carved, which now is situated in front of the Kw’umut Lelum centre on Centre Street in Nanaimo. (Karl Yu/News Bulletin)
House post representative of work of Kw’umut Lelum in Nanaimo

Snuneymuxw First Nation artist Noel Brown’s carved red cedar house post unveiled Friday, April 16

(Black Press file photo).
UPDATED: Multiple stabbings at Vancouver Island bush party

Three youths hospitalized after an assault in Comox

A syringe is loaded with COVID-19 vaccine at a vaccination clinic run by Vancouver Coastal Health, in Richmond, B.C., Saturday, April 10, 2021. THE CANADIAN PRESS/Jonathan Hayward
B.C. to open up COVID vaccine registration to all B.C. residents 18+ in April

Registration does not equate to being able to book an appointment

Russ Ball (left) and some of the team show off the specimen after they were able to remove it Friday. Photo supplied
Courtenay fossil hunter finds ancient turtle on local river

The specimen will now make its home at the Royal BC Museum

Selina Robinson is shown in Coquitlam, B.C., on Friday November 17, 2017. British Columbia’s finance minister says her professional training as a family therapist helped her develop the New Democrat government’s first budget during the COVID-19 pandemic, which she will table Tuesday. THE CANADIAN PRESS/Darryl Dyck
B.C. finance minister to table historic pandemic-challenged deficit budget

Budget aims to take care of people during pandemic while preparing for post-COVID-19 recovery, Robinson said

Each spring, the Okanagan Fest-of-Ale is held in Penticton. This year, as a result of the COVID-19 pandemic, the festival will not be held. However, beer is still available. How much do you know about this beverage? (pxfuel.com)
QUIZ: How much do you really know about beer?

Put your knowledge to the test with this short quiz

Most Read