Ontario stands firm on 12-week interval for AstraZeneca doses — against experts' advice

Ontario stands firm on 12-week interval for AstraZeneca doses — against experts' advice

Citing the need for speed against the growing threat of the coronavirus delta variant, infectious diseases specialists say they disagree with the Ontario government's decision to maintain a 12-week waiting period before people who received a first dose of the AstraZeneca-Oxford vaccine can get their second dose.

That rule applies even for people who got a first shot of AstraZeneca and are choosing an mRNA vaccine (Pfizer-BioNTech or Moderna) for their second. 

In contrast, people in Ontario who received an mRNA vaccine as their first dose can get their second one after just eight weeks. 

Other provinces, including B.C., Alberta and Quebec, are now recommending that everyone get their second dose after eight weeks, regardless of whether the first jab was AstraZeneca or an mRNA vaccine. 

Speed vital to counter delta variant

Infectious disease experts widely agree that the two doses required to be fully vaccinated against coronavirus will offer stronger protection against the delta variant of the virus, which has become the dominant strain in the U.K. and is gaining momentum in Canada. 

“The push should really be to get those second doses in fast,” said Dr. Isaac Bogoch, an infectious disease specialist at Toronto General Hospital, who is also a member of Ontario's COVID-19 Vaccine Distribution Task Force.  

“Treat a crisis like a crisis,” Bogoch said. “Even though case numbers are declining and hospitals are decompressing and vaccines are rolling out — and clearly that's all good — you still have a delta variant. You still are watching this encroach on the existing variants here.

“You also have a crystal ball. You can look at the United Kingdom and see exactly what's happening there,” he said. “This variant will find unvaccinated people and it will find undervaccinated communities. It's doing that in the U.K. and it will do the exact same thing here with us.”

Getting not only first doses but also second doses into arms as quickly as possible after the four-week mark (which experts agree is the minimum interval for effectiveness) is vital to stopping that from happening, Bogoch said. 

Decision driven by data, health ministry says

But in an email to CBC News on Thursday, Ontario's ministry of health said its decision is driven by scientific data.   

“We know that two doses of AstraZeneca at a 12-week interval provides a better immune response than over a shorter interval,” the ministry said. 

The 12-week interval for people who got the AstraZeneca shot will still apply in delta variant “hotspots,” the ministry confirmed to reporters later — even as it starts a program to accelerate second shots for people who got mRNA vaccines in those areas.  

Dr. Dirk Huyer, Ontario's chief coroner and another member of the province's vaccine task force, also defended the 12-week duration between doses, noting that the move is based “upon the data that's available.”

There isn't much information yet, Huyer said, about the optimal timeframe between a first dose of AstraZeneca and a second dose of either Pfizer-BioNTech or Moderna. 

“We will continue to look at everything that's available to us,” he said. 

Later on Thursday, Dr. Barbara Yaffe, Ontario's associate chief medical officer of health, told reporters that officials would continue to look for more guidance on how to space out mixed doses for people who got a first shot of AstraZeneca but want their second shot to be an mRNA vaccine. 

12-week interval not needed, experts say     

It's true that randomized control trials have shown two doses of AstraZeneca generate the optimal immune response if they are 12 weeks apart, said Dr. Caroline Quach-Thanh, pediatric infectious disease specialist and medical microbiologist at Chu Ste. Justine in Montreal.

But there's no evidence that's the case when people choose an mRNA vaccine instead of AstraZeneca as their second dose, she said. 

“You don't need to wait 12 weeks,” said Quach-Thanh, who is the former chair of the National Advisory Committee on Immunization (NACI), but was not speaking on NACI's behalf. 

WATCH | Infectious disease expert says Ontario making wrong call on 12-week dose spacing:

Ontario stands firm on 12-week interval for AstraZeneca doses — against experts' advice

Ontario accelerates 2nd vaccine doses, but not for AstraZeneca

CBC News

5 hours ago

3:19

Dr. Anna Banerji, a pediatric infectious diseases specialist, explains why she believes the Ontario government is making the wrong decision when it comes to maintaining the 12-week gap between first and second doses of the AstraZeneca-Oxford COVID-19 vaccine. 3:19 

“I think what comes into play here is to balance,” she said. “What needs to be discussed at the Ontario level is this gain in earlier protection for more people when they get their second dose.”

“What we all want is to be fully vaccinated before this delta variant starts to get transmitted very actively in the community.” 

Dr. Anna Banerji, an infectious diseases specialist at St. Michael's Hospital in Toronto, said that even if someone is taking AstraZeneca for both their doses, the urgency of protecting people against the delta variant is the more important consideration at this point in the pandemic.    

“The risk of exposure is highest now,” Banerji told CBC News Network on Thursday. “There's no reason to wait 12 weeks.”

News Related

OTHER NEWS

Mum reveals $10 reason son can't have 'normal life'

For Lykera Parker, seeing another child walk can trigger a pang of sadness. Because she knows that while her son Kalarny is as bubbly and outgoing as any four-year-old, he ... Read more »

COVID-19: Cases fall in the Netherlands and UK, while Italy and Romania push vaccines

While COVID-19 cases fall in some European countries, others fear a fourth wave of infections is underway. Cases in the Netherlands have fallen by 44% compared to last week, according ... Read more »

Schools implement mask mandates even as some states impose bans; US reports one case every second: Live COVID-19 updates

The U.S. Department of Education Monday released a roadmap for the return to school this fall, encouraging districts to invest in physical and emotional support for students. Among the roadmap’s ... Read more »

Cobblestone stones honor WWII gay and lesbian resistance fighters

Karel Pekelharing stone. Photo: DutchNews.nl Nine Jewish gay and lesbian resistance figurines are to be given their own “Stolperstein” or commemorative street tiles in front of their last known address. ... Read more »

Covid UK news – live: Vaccine to be offered to 16 and 17-year-olds as UK sees highest deaths since mid-March

✕ Close Coronavirus in numbers The coronavirus vaccination programme looks set to be rolled out to more than a million 16- and 17-year-olds. It is expected ministers will on Wednesday ... Read more »

Obese mice lose weight ‘sweating out' fat in an immune system experiment, despite eating more

In search of better treatments for type 2 diabetes and other consequences of obesity, Taku Kambayashi has long wondered if he could harness a bodily function that most think about ... Read more »

NYC will have the first government-issued vaccine mandate in the US. Here's what we know.

NYC Mayor Bill de Blasio just mandated proof of vaccination for indoor restaurants, gyms and performance venues. Here’s how that will work. Read more »

Peak hospital admissions seems to have been reached, 44% fewer new infections

Increase in IC In the past week, 541 new COVID-19 hospitalizations were registered compared to 564 the week before. “In the past week, there were 130 new admissions to the ... Read more »

The Path to Forgiveness When Someone Hurts You: How to Forgive, Let Go, and Protect Yourself

When you’ve been hurt by someone you trust, you might feel angry or resentful, especially if it keeps happening. Forgiving the person who is hurting you can rid you of ... Read more »

How to Boost Your Confidence (13 Steps to Help Your Social Anxiety)

Are you sometimes nervous to speak up and say what’s on your mind? It’s okay to be a little shy every now and then, but it might prevent you from ... Read more »

This South Korean company has figured out how to get the best night's sleep. Does sleep tech work?

A lack of sleep not only makes us grumpy in the mornings but it can also affect our health too. There are a range of gadgets out there with many ... Read more »

NHS must work in “new ways” to deliver care, says new chief executive

Amanda Pritchard during a visit to University College Hospital London, following the announcement of her appointment as the new chief executive of the NHS in England. (PA) The health service ... Read more »

3 ways to show you've gotten the COVID-19 vaccine

Did you misplace your vaccine passport? Here are three other ways you can prove you’ve been vaccinated. Read more »

Covid-19 antibody test: what does your result mean? Why a high score is good but doesn't tell the whole story

Standing in a taxi queue recently I overheard a middle-aged man say to a woman of similar age ahead of him in line, “I got 650”. Whatever he was referring ... Read more »

One-third of all COVID cases reported in Florida and Texas; US reaches 70% of partially vaccinated adults: COVID-19 updates

Florida and Texas had one-third of all COVID cases reported last week, White House COVID-19 Response coordinator Jeff Zients said during a Monday news conference. Florida broke two records — ... Read more »

Rabobank to compensate customers who have paid too much interest

Photo: Rabobank Rabobank is working to settle thousands of customers who have paid large amounts of interest on consumer loans, Cooperative Bank said Tuesday. The decision focuses on the high ... Read more »

Covid UK news - live: PM U-turns on amber watchlist as England could be ‘over the edge' of third wave

✕ Close Boris Johnson hints at U-turn on amber watchlist Plans for an “amber watchlist” have been abandoned as ministers prepare to review the traffic light system which will decide ... Read more »

How to Verify a Physician's License in California

Before you choose a physician for any type of treatment, it’s always a good idea to verify their license. This assures you that their license is in good standing and ... Read more »

Sailing Bronze has won a total of 19 Dutch medals and will win even more.

Annemiek Bekkering and Annette Duetz during the race. Photo: Olaf Kraak ANP In the disappointing medal race of Sailor Annemiek Bekkering and Annette Duetz, she was pushed back to the ... Read more »

From AI to ice vests: How Tokyo 2020 athletes are adapting to the hottest Olympics ever

Tokyo 2020 is likely to go down in history as the hottest modern Olympic and Paralympic Games ever. Daily high temperatures in the Japanese capital have hovered around 31C throughout ... Read more »

How to Use a Monocular

A monocular is like a small telescope. It is smaller and lighter than binoculars while packing the same power. To use a monocular, make sure that you keep a firm ... Read more »

Poorer communities see twice as many smoking related cancers as richer areas, says study

Smoking is linked to poverty and is causing more cancers in poorer communities (Getty Images/iStockphoto) There are nearly twice as many cancers caused by smoking among the poorest people in ... Read more »

Paramedics left in tears from ‘unsustainable demand', warns union

Unison has warned ambulance chiefs that the pressure is taking its toll on their workforce (Getty) Paramedics are being left in tears at the end of stressful shifts, with some ... Read more »

How to Use Apple Health

This wikiHow teaches you how to get started with Apple Health on your iPhone. The Health app makes it easy to access your important health information, including your medical history, ... Read more »

How to Understand Social Distancing

The term “social distancing” is all over the news, but what does it really mean? This term refers to staying a specific distance away from other people to help prevent ... Read more »

How to Treat a Bruised Thigh Muscle

Ouch! A bruised thigh is no joke. The front of your thigh is composed of large muscles called your quadriceps, and anybody who’s ever taken a direct hit there can ... Read more »

How to Treat Tunnel Wounds

A tunnel wound is a secondary wound that occurs alongside a primary wound, and it’s usually caused by an infection or pressure. This kind of wound extends into layers of ... Read more »

How to Treat Overmethylation

Methylation is a fairly complex process, but basically, it’s the natural process where methyl groups (one carbon and three hydrogen atoms) are transferred throughout your body. This happens billions of ... Read more »

How to Treat Numbness in Legs and Feet

Numbness in your legs and feet can cause discomfort and awkwardness, but it’s usually no cause for alarm. If you sit or stand in the same position for an extended ... Read more »

How to Treat Liver Fibrosis

Your liver is an incredible organ—it can grow back from almost nothing. But if it’s damaged too often, it can lead to a condition called fibrosis. The good news is ... Read more »

50 per cent vaxxed is not enough to safely lift restrictions: Doherty Institute

If NSW reaches its target of 6 million Covid-19 vaccinations by the end of the month it will still be “a long way” from being safe from the virus, according ... Read more »

How to Treat Crepitus

Crepitus is a general term for the crackling or popping sound made by a joint. This is typically caused by cartilage or soft tissue rubbing against a joint during movement, ... Read more »

How to Treat Cold Feet

Having cold feet is a pretty common problem, especially during the wintertime. However, if you have persistent cold feet, you could have an underlying condition such as Reynaud’s phenomenon. Fortunately, ... Read more »

How to Treat Buttock Folliculitis

Folliculitis is a common condition causing inflamed hair follicles and a raised rash. While it can occur anywhere on your body, the buttocks are a common area for an outbreak. ... Read more »

'People who do not want to be vaccinated may go elsewhere': Court backs Indiana University mandate

INDIANAPOLIS — Students who don’t like Indiana University’s COVID-19 vaccine requirement can go elsewhere for their education. That was the message delivered by the 7th Circuit Court of Appeals in ... Read more »

How to Take a Mankind Unwanted Kit

A Mankind Unwanted Kit is made up of 1 pill called mifepristone and 4 pills called misoprostol that your OB/GYN can give you. These are taken to terminate an unwanted ... Read more »

How to Take Control of Your Health

No matter what our existing health, financial, mental, economic, or social situation is, there are things we can each do to take (better) control of our own health. No one ... Read more »

How to Take Care of Yourself

Taking care of yourself can feel like a really big task, but it doesn’t have to be overwhelming. Learn to manage your physical, mental, and emotional health so that you ... Read more »

Japanese shadow painting master delivers hope, delight in Seoul

Read more »

How to Store Ascorbic Acid

Ascorbic acid, or ascorbate, is another name for vitamin C. Ascorbic acid helps your body grow and repair itself and is an essential nutrient. Unfortunately, it is also very delicate ... Read more »