Coronavirus: When will the waiting time between double vaccinations be reduced?

Ottawa-National jurisdictions follow the National Vaccine Commission’s recommendation to extend the time between the first and second doses of the two-shot COVID-19 vaccine to a maximum of four months. But as Canada’s vaccine supply is set to increase, will the state begin to reduce the spacing between shots?

CTVNews.ca provides current policies for some states, whether some states plan to change their approach in the near future, and where is Canada’s unusually long COVID-19 vaccination interval. I looked it up.

National Advisory Committee on the Basics of Immunization (NACI) — Independent Volunteer Advisory Committee of Healthcare Professionals for Vaccine Use RecommendationsRecommended on March 3 Postponing the second shot to spread COVID-19 protection as much as possible with the limited dose Canada had, despite the manufacturer’s advice.

At a follow-up press conference on April 7, NACI Vice-Chair Dr. Sherry Dikes said early efficacy data on what infectious disease specialist Dr. Isaac Bogotti calls a “speed of first dose” strategy. 16 weeks after the first option was feasible, the time people have to do The actual wait is “expected to be low”.

NACI is likely to have shot intervals closer to the manufacturer’s recommended intervals as supply increases over the next few months, with a second dose scheduled 1.5 to 2 months after the first dose. I estimated.

Federal government 44 million doses By the end of June.

With this commitment, some states have announced their intention to make the first shot available to all eligible adults by the end of June. On Thursday, both Ontario and Quebec announced that they would open reservations to everyone over the age of 18 in May.

At least in Ontario, the move hasn’t changed the state’s approach to a second dose yet, but solicitor Sylvia Jones could do so if the federal government announced a further increase in shipments. I will.

“If you have enough, consider bringing the first and second doses closer together, but it is very important to take the first dose to many who are interested and willing to take it.” She said.

State difference

NACI states that the person at highest risk should be prioritized and a second dose should be delivered as soon as possible. NACI states that the person at highest risk should be prioritized and a second dose should be delivered as soon as possible. The two states that are paying attention to this aspect of NACI’s guidance are Alberta and Ontario.

In Alberta, caregivers, people living a designated supportive life, people receiving certain types of cancer treatment, or taking medications that cause immunodeficiency have been given the first dose. We are able to schedule a second dose 21-28 days later.

Ontario is a resident of long-term sanatoriums and other elderly homes, immunized people in remote, isolated indigenous communities, transplant recipients, and active recipients of certain medical conditions. Treatments that provide other people with a second dose every 21-42 days.

Several states, including Nova Scotia, have shown no positive consideration of reducing the time between doses immediately, which is what Manitoba is currently discussing.

“We are about to finalize the full picture of the second dose plan. We hope to announce it fairly early next week. But what I can say about the second dose is: By the time it rolls, it will be a scenario of high vaccine supply to the state, “Johanu Botha, co-leader of the Manitoba Vaccination Task Force, said at a briefing on April 28. ..

“4 months is a medical recommendation in terms of how long the second dose can be extended, not operational. Before anyone takes the second dose for anyone who wants it. , We don’t wait that long. “

In Ontario, Bogok, who is also a member of the state’s COVID-19 Vaccine Distribution Task Force, shared similar feelings.

“It’s no exaggeration to say that you probably won’t wait four months for your second dose. The keyword is probably,” Bogotti said in a recent interview with CTV News.

Concerns about delays

Longer waits between shots are advice in contrast to the timeline included in Health Canada’s approval of these vaccines and are consistent with the pharmaceutical company’s shorter interval guidance.

For example, Pfizer recommends a second dose 21 days later. Moderna recommends a 28-day interval, and AstraZeneca suggests that the second shot be given 4-12 weeks after the first shot.

As a regulator, Health Canada is responsible for approving each vaccine for use in Canada, but NACI’s job is to suggest how to use the vaccine.

In a March statement, Pfizer acknowledged that some countries had increased dosing intervals, but pharmaceutical giants did not evaluate the safety and efficacy of different dosing schedules.

“Vaccine protection appears to begin 12 days after the first dose, but two doses of the vaccine are required to provide maximum protection against disease, 95% vaccine efficacy. There are no data showing that protection after the first dose lasts after 21 days. ” Statement Pfizer.

This severance raised concerns about whether Canada had entered “undeveloped territory.” As Conservative Prime Minister Erin O’Toole recently mentioned, it is the only country that has implemented delays of up to four months between doses.

Despite these concerns, the COVID-19 vaccine used by Canada appears to provide strong levels of immunity after a single dose as more realistic clinical data are published.

What the data shows

Not all states are doing their own research on the effectiveness of extending dosing intervals, but in British Columbia, a single dose to caregiver residents and health care workers, according to the State Department of Health. The efficacy of the vaccine after administration is shown as follows. “80% or more within 2 to 3 weeks after vaccination”.

“We are learning that we can maintain this high level of protection by extending the second dose to at least 16 weeks. In fact, extending this interval will make it more durable and longer lasting in the long run. Protection may be available, “says the British Columbia Department of Health. Statement spokesman Mariel Tounsi.

Between January and March, mRNA Pfizer and Moderna will release new data released by the US Centers for Disease Control and Prevention (CDC) on April 28. The vaccine was 64% effective For COVID-19 hospitalization after one shot.

“A careful look at the data from the Phase 3 trial shows that about 14 days after the first dose, enhanced protection is actually seen,” said the Canadian Institute of Health. Science Director Dr. Charu Kaushic in a recent interview with CTV News.

Experts say that the degree of effectiveness after a single dose is not sufficient for Canadians to disappoint guards after the first shot, but Kaushic says in the long run, a widespread vaccine. He said he chose to inoculate. As the population grows faster, the overall spread of COVID-19 can be curtailed.

She said this was what was seen to be happening in the UK, which also extended the dosing interval and provided citizens with shots every three months.

In data from several state health agencies and anecdotal reports from doctors treating COVID-19 patients, people are still seriously ill with COVID-19 after the first shot. So there are calls from frontline people and scholars. Political and public health leaders The protection people have While waiting for them to be fully vaccinated.

“It’s very important to understand what you can do safely with one or two vaccines. Another upcoming challenge we already have to think about is the person who took the first dose. Is actually a second dose, “Heidi Tworek, a professor of health communication at the University of British Columbia, said in a recent interview with CTV. news.

Basis for details of the new document

A recently submitted response from the Public Health Agency of Canada (PHAC) seeks to shed some light on where NACI is currently standing on a proposal to delay a second dose.

PHAC responded to questions from conservative parliamentarians and health critic Michelle Lempel Garner asking what scientific evidence was used and what deliberations were recommended, and NACI issued Canadian population data. He said he relies on peer-reviewed preprint studies as well. And overseas. We also took into account historical experience with double-dose vaccines and immunological principles when considering the decisions of the three meetings before voting for the issuance of recommendations.

“Experience with other multi-dose vaccines after a single dose suggests that sustained protection may last for more than 6 months in adolescents and adults. Clinical trial participants and public programs Long-term follow-up of participants vaccinated through will help determine the duration of protection after both one and two doses of the COVID-19 vaccine, “partially PHAC’s response. Please read.

Authorities also collect weekly data in some Canadian jurisdictions to monitor the effectiveness of extended intervals, and if supply, epidemiology, or effectiveness conditions change, NACI will He said he would consider changing the guidance.

Now seen elsewhere in the NACI guidance — including recent ones Eligible age for AstraZeneca Vaccines — States can choose to take a different approach at any time, regardless of the position of this volunteer organization.

When can your strategy change?

With all this in mind, at this point in the rollout, there seems to be little movement to reduce the wait time of up to 4 months, but that doesn’t mean it won’t happen.

The states in which the second dose is suspended until everyone who wants it receives the first dose may change on a daily basis in Canada.

If the state sticks to prioritizing the first vaccination until the end of June, by July, high-volume vaccination efforts should focus on arming the second vaccination. This is except for Canadians who start vaccination with a single Johnson & Johnson COVID-19 vaccine.

Given the federal government’s plan to fully vaccinate all eligible adults by the end of September, first and second vaccinations for individuals who receive only the first vaccination in June. The waiting time between should start to get shorter.

“Within next month or two months, many people you know can be vaccinated, and if enough vaccines are available, we will go back and give more people a second shot. I’m sure we can try to give it, “said Kausic. “People are now given a date to enter August, as you know, but that doesn’t mean you may not be able to get a second dose sooner.”

by CTV News Vaccine Tracker, Approximately 12 million people in Canada were initially vaccinated, and approximately 1 million Canadians (many of whom should have started COVID-19 vaccination in winter prior to this strategic change) were fully vaccinated. It has been.

Using files from Annie Bergeron-Oliver on CTV News