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dose came from a variety of real life scenarios, both in Canada and abroad, although NACI said many of the studies had not yet been peer reviewed.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

An Interior Health nurse administers Pfizer-BioNTech COVID-19 vaccines to seniors and care aids in Kelowna on Tuesday, March 16, 2021. (Phil McLachlan/Kelowna Capital News)
105 new COVID-19 cases in Interior Health

Just over 8,000 new vaccine doses administered in the region for a total of 158,000 to date

Sand, sandbags will be available at three different locations for Mill Creek for property owners. (Black Press Media file photo)
City prepares for possible Mill Creek flooding

The City of Kelowna is providing sand at three different locations for property owners near Mill Creek

A still from the video taken of a violent arrest on May 30, 2020 in downtown Kelowna. (File)
Kelowna Mountie charged with assault for caught-on-camera violent arrest

Const. Siggy Pietrzak was filmed punching a suspected impaired driver at least 10 times during an arrest

(Pexels photo)
Okanagan film boom owes to industry’s strong pandemic response: Sandhu

Vernon-Monashee MLA Harwinder Sandhu lauded the local film industry’s adaptation to the pandemic

Prospera Place in Kelowna. (Marissa Baecker/Shoot the Breeze)
Kelowna Rockets return to the ice after COVID-19 quarantine

All individuals within the team cohort tested negative for COVID-19 earlier this week

Arlene Howe holds up a picture of her son, Steven, at a memorial event for drug overdose victims and their families at Kelowna’s Rotary Beach Park on April 14. Steven died of an overdose at the age of 32 on Jan. 31, 2015. (Aaron Hemens - Kelowna Capital News)
Moms Stop the Harm members placed crosses Wednesday morning, April 14, on Rotary Beach in memory of children lost to drug overdoses. (Aaron Hemens - Capital News)
Kelowna mothers remember children lost to the opioid crisis

It has been five years since illicit drug deaths was announced a public health emergency

Demonstrators at the legislature on April 14 called on the province to decriminalize drug possession and provide widespread access to regulated safe supply across B.C. (Jake Romphf/News Staff)
Rally calls for decriminalization, safe supply on 5th anniversary of overdose emergency declaration

From 2016 to the end of February, 7,072 British Columbians died due to overdose

A Keremeos family lost their home after a fire shortly before midnight on April 13. No injuries were reported. (Contributed)
Keremeos home destroyed in late-night fire

The family inside was unharmed

Join Black Press Media and Do Some Good
Join Black Press Media and Do Some Good

Pay it Forward program supports local businesses in their community giving

Naloxone
Op/Ed: Interior Health CEO speaks on five years of strides and challenges in overdose crisis

In 2020, close to 4,000 people across IH had access to opioid medications

Somewhere in the pack being celebrated by his teammates is Vernon Vipers forward Zack Tonelli, who scored in overtime Wednesday afternoon, April 14, to give the Snakes a 6-5 win over the Salmon Arm Silverbacks in B.C. Hockey League pod play at Kal Tire Place. (Liza Mazurek - Vernon Vipers Photography)
Vernon Vipers bite Salmon Arm Silverbacks in OT

Snakes blow 5-3 third-period lead, rally in extra time for 6-5 pod play result over rivals

(Government of Canada)
Liberal MP caught stark naked during House of Commons video conference

William Amos, in Quebec, appeared on the screens of his fellow members of Parliament completely naked

New parking meters have been installed on Main Street, Ellis Street, Front Street, Nanaimo Avenue and Padmore Avenue in Penticton. (City of Penticton photo)
Pay parking now in effect in downtown Penticton

A spot downtown will now cost you $2 per hour

Provincial health officer Dr. Bonnie Henry updates B.C.’s COVID-19 situation at the B.C. legislature, Feb. 1, 2020. (B.C. government)
B.C.’s COVID-19 case count jumps to 1,168 Wednesday, nearly 400 in hospital

Now 120 coronavirus patients in intensive care, six more deaths

Most Read