Dr. Bonnie Henry, B.C.'s Provincial Health Officer, is expected to announce her decision on whether to change the recommended interval for the COVID-19 vaccine booster this week.JONATHAN HAYWARD/The Canadian Press
Charting the rate of COVID-19 among seniors in B.C.’s long-term care homes after they’ve received the first shot of the vaccine shows exactly what you’d want to see: a marked decline in infections, starting two weeks after immunization. As the pandemic heads into its second year in the province, this is one of the most encouraging indicators to be found.
Data from the BC Centre for Disease Control, or BCCDC, suggest most of the benefit from the two vaccines that have been in use in Canada – Pfizer–BioNTech and Moderna – is delivered in that first jab.
British Columbians will get more detail on Monday on the next phase of the province’s vaccine plan. Now that most residents in long-term care homes have been immunized, those at greatest risk of getting seriously ill or dying of COVID-19 in the province are the elderly who are living in the community. They will have priority in this next stage of immunization.
Monday’s announcement on the immunization plan’s Phase 2 presents an opportunity to revisit the policy on when booster shots should be delivered. The current target is to deliver a booster within 42 days of the first shot, but there is mounting evidence that the interval can be extended, so that B.C. can stretch its still-limited vaccine supply.
The author of the BCCDC’s research on vaccine efficacy is Danuta Skowronski, who heads the centre’s influenza and emerging respiratory pathogens team. Dr. Skowronski is emphatic that B.C. should spread out the interval between the first shot and the booster. Her research mirrors findings in Quebec, Scotland and Israel: The consensus is growing that the first shot provides protection of 80 per cent or better, and recipients can safely wait as much as 90 days for their booster without losing that benefit.
Canada pre-purchased millions of doses of seven different vaccine types, and Health Canada has approved four so far for the various provincial and territorial rollouts. All the drugs are fully effective in preventing serious illness and death, though some may do more than others to stop any symptomatic illness at all (which is where the efficacy rates cited below come in).
- Also known as: Comirnaty
- Approved on: Dec. 9, 2020
- Efficacy rate: 95 per cent with both doses in patients 16 and older, and 100 per cent in 12- to 15-year-olds
- Traits: Must be stored at -70 C, requiring specialized ultracold freezers. It is a new type of mRNA-based vaccine that gives the body a sample of the virus’s DNA to teach immune systems how to fight it. Health Canada has authorized it for use in people as young as 12.
- Also known as: SpikeVax
- Approved on: Dec. 23, 2020
- Efficacy rate: 94 per cent with both doses in patients 18 and older, and 100 per cent in 12- to 17-year-olds
- Traits: Like Pfizer’s vaccine, this one is mRNA-based, but it can be stored at -20 C. It’s approved for use in Canada for ages 12 and up.
- Also known as: Vaxzevria
- Approved on: Feb. 26, 2021
- Efficacy rate: 62 per cent two weeks after the second dose
- Traits: This comes in two versions approved for Canadian use, the kind made in Europe and the same drug made by a different process in India (where it is called Covishield). The National Advisory Committee on Immunization’s latest guidance is that its okay for people 30 and older to get it if they can’t or don’t want to wait for an mRNA vaccine, but to guard against the risk of a rare blood-clotting disorder, all provinces have stopped giving first doses of AstraZeneca.
- Also known as: Janssen
- Approved on: March 5, 2021
- Efficacy rate: 66 per cent two weeks after the single dose
- Traits: Unlike the other vaccines, this one comes in a single injection. NACI says it should be offered to Canadians 30 and older, but Health Canada paused distribution of the drug for now as it investigates inspection concerns at a Maryland facility where the active ingredient was made.
How many vaccine doses do I get?
All vaccines except Johnson & Johnson’s require two doses, though even for double-dose drugs, research suggests the first shots may give fairly strong protection. This has led health agencies to focus on getting first shots to as many people as possible, then delaying boosters by up to four months. To see how many doses your province or territory has administered so far, check our vaccine tracker for the latest numbers.
While the vaccines are still scarce, such a delay would allow the province to immunize more people sooner.
Tracking Canada’s COVID-19 vaccine rollout plans: A continuing guide
Bonnie Henry, the Provincial Health Officer, expects to announce her decision on whether to change the recommended interval for the booster this week. She is hoping that the National Advisory Committee on Immunization will first update its recommendations to help determine an appropriate interval based on the most recent research.
But the decision is not just about the data, she said.
Britain and Quebec have shifted to a 90-day interval already, but Dr. Henry is concerned that too many changes can undermine public trust. B.C. has already changed the recommended interval twice, extending the period as the science dictated – but conveniently, those changes accommodated vaccine shortages.
Earning and keeping broad public trust is critical. B.C. has had remarkable success in overcoming vaccine hesitancy. A survey conducted in December by SafeCare BC, the workplace safety association for long-term care homes, found only 57 per cent of staff want to get the shots. To date, the rate of vaccination among those workers is roughly 95 per cent.
But the vaccine shortages have created fresh anxiety. “A lot of public discourse right now is really negative about the immunization programs,” Dr. Henry said. There are groups that think they should have higher priority, and there are concerns the province isn’t providing certainty quickly enough. Then, if the program is rushed, they will be upbraided for anything that doesn’t work – as health officials in Alberta learned last week after a glitch-filled launch of general COVID-19 immunization bookings.
B.C. will hope that its next rollout will go smoothly, to build back some of the confidence that it lost when the federal government was unable to deliver much of the promised vaccines.
“We do have to take into account the acceptability and confidence in the vaccine program, and a whole bunch of other things, not just what the data is telling us,” Dr. Henry said in an interview.
She said B.C. will still try to meet the 42-day booster deadline for those who have already had their first shot, “because that’s the contract we made with people when they received their first dose,” she said.
But she said this week would be an optimal time for adjustments. “Now is good timing, because we’ve had a period of time where we have not given a lot of first doses. So, we can say, starting at this time, we’re going to be moving forward with this strategy.”
And if the data support the change, it would be good news for the many people still anxiously awaiting their turn. “Delaying for 90 days for the second dose – if that turns out to be supported by the evidence that we have so far – will allow us to provide first doses to way more people.”
Prime Minister Justin Trudeau says more Canadians will get vaccinated sooner now that a third vaccine has been approved in Canada and more doses of it have been secured. Health Canada's chief medical adviser Dr. Supriya Sharma says the AstraZeneca vaccine and all the others Health Canada has approved are safe and effective against COVID-19.
The Canadian Press
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