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What the level of COVID-19 immunity in Canada could mean for the vaccine hunt – CBC.ca

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This is an excerpt from Second Opinion, a weekly roundup of health and medical science news emailed to subscribers every Saturday morning. If you haven’t subscribed yet, you can do that by clicking here.


It is a constant refrain during the pandemic: Life won’t get back to normal without a vaccine.

Efforts to create one depend on better understanding what happened in the immune systems of patients who have recovered from COVID-19, and whether they have any protection from the disease now that they have antibodies to the coronavirus that caused it.

In Canada, the national Immunity Task Force has so far examined antibody levels from the blood of 35,000 Canadians across the country who donated blood or who had their blood drawn for medical tests in British Columbia, Alberta and Ontario.

The task force found that the level of coronavirus antibodies in the population, or seroprevalence, barely registered in some cases. 

“The message is clear,” said Dr. David Naylor, co-chair of the task force. “Immunity in the Canadian population remains very low.” 

Héma-Québec’s data suggests 2.23 per cent of samples had antibodies. Samples from Montreal were highest at 3.05 per cent, Naylor said. Samples from B.C., Alberta and Ontario fell in the one per cent range.

With so few people carrying antibodies, everyone in Canada remains at risk for infection. 

“Broad population susceptibility, in turn, means that caution is required this fall as schools and worksites reopen,” Naylor said in an e-mail interview. “These results also underscore the continuing urgent need for safe and successful deployment of effective vaccines against COVID-19.”

Low infection rate, low immunity

But while a low rate of potential immunity leaves many Canadians susceptible, a higher rate brings other issues.

Dr. Allison McGeer, a member of the task force’s leadership team and an infectious disease physician in Toronto, points to hard-hit New York, where early testing found more than 13 per cent of people had developed antibodies. 

“It’s important to remember that the price of being at 13 per cent was a very large number of dead people and catastrophic health care for six or eight weeks,” McGeer said.

It’s not yet known how long coronavirus antibodies remain in the body, or whether their presence, and at what level, protects someone against reinfection. There have been documented cases of patients reinfected months after they recovered.

But Naylor called those reinfections “outliers” among the millions of cases of COVID-19 worldwide. 

Still, they add to the uncertainty about how both natural immunity and vaccines could work in the long term.  

WATCH | Reinfections add to vaccine challenges: 

Three confirmed cases of COVID-19 reinfection raise concerns about how common it might be and how effective a vaccine will be as the virus appears to mutate. 1:57

Kelvin Kai-Wang To of the University of Hong Kong’s microbiology department co-authored a paper on the first documented reinfection, which used genome sequencing to show the first and second infections were caused by different viral strains.

He said the findings suggest that the best hope for stemming the pandemic remains a vaccine.

That’s because SARS-CoV-2, the virus that causes COVID-19, may persist in people worldwide, as other human coronaviruses do — even if patients acquire natural immunity after infection.

“Our study only shows that immunity induced from natural infection cannot prevent reinfection for our patient,” he said. “Vaccine-induced immunity can be much stronger and last much longer than infection-induced immunity.”

More infected than known

For Dawn Bowdish, Canada Research Chair in aging and immunity and an associate professor at McMaster University in Hamilton, the Canadian seroprevalence results are good news.

“It means Canadians are doing the right things and not too many of us were infected,” said Bowdish, who is independent from the task force. “It also does tell us that it’s higher than the number of infections that we knew about.”

Serology helps uncover the number of asymptomatic carriers of the virus, whereas most testing has been done on people with symptoms. 

“It speaks to the importance of doing lots and lots of testing for even people with very minor symptoms.” She also notes that the research to date suggests that children with COVID-19 are less likely to show symptoms than adults.

School could bring fundamental shift

Underscoring how screening for symptoms alone can miss COVID-19 cases in children, researchers in South Korea reported that of 91 children who were positive for the virus, 22 per cent were asymptomatic. Half were over the age of 10.

“We are expecting a fundamental shift in the dynamics of the pandemic … as we start opening up and go back to school,” Bowdish said.

Students Lucas Provias, 16 and Vanessa Trotman, 15, take part in a return-to-school demonstration in Toronto. The dynamics of the pandemic could shift as classes resume. (Evan Mitsui/CBC)

Bowdish believes “no COVID is good COVID,” and pursuing near elimination should be the collective goal in Canada because of its long-term health consequences in people of all ages, including young adults, a demographic that’s seeing more cases across Canada. 

Dr. Caroline Quash, a pediatric infectious disease physician and medical microbiologist in Montreal, is encouraged by what she saw when she helped treat some of the 63 children and pregnant women with COVID-19 that have come through Montreal Children’s Hospital so far.

“What’s very interesting is, I think, that the immune system of children is much better equipped to face COVID than adults,” said Quash, who is also a member of the immunity task force. “With the same number of viruses in their nose, and sometimes even higher, they don’t develop any of that hyperinflammation that brings adults to the hospital. Somehow — and that’s what research needs to tell us — they deal better with this virus.”

Advantage of kids’ blank slates

Bowdish said the difference between the immune systems of adults and those of children might offer some clues to designing vaccines.

A medical lab technician draws a blood sample for a coronavirus antibody test at the B.C Centre for Disease Control. Experiments to sort out the relationship between disappearing antibodies and recall of immune cells will take longer. (Ben Nelms/CBC)

In many of the adults who died due to COVID-19, the immune response was too strong and the wrong kinds of immune cells went into organs and caused damage. That reaction hasn’t been as prevalent in children.

Children’s immune systems also tend to respond better to many vaccines, Bowdish said, because they tend not to have “immune memory” — the immune system’s recognition of an antigen the body has previously encountered.

Vaccines for adults are more complicated, Bowdish said.

She pointed to two main forms a coronavirus vaccine could take.

It could be like the tetanus vaccine, which requires a booster every 10 years because the immune response doesn’t last. Or, “if we’re really lucky,” it could be like the measles vaccine, where even if antibody levels decrease over a year, they pop back up if reinfected.

“We need time to figure this out,” Bowdish said.

Experiments are underway worldwide to sort out the relationship between disappearing antibodies and recall of immune cells with a memory of the virus. When safe and effective vaccines become available, that’s something the task force hopes to measure.

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Sudbury health officials confirm eighth new COVID-19 case in 8 days – CTV Toronto

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SUDBURY —
Health officials in Sudbury have confirmed the eighth new case in just over a week.

Public Health Sudbury & Districts say this latest case appears to be the result of community spread, with the exposure being unknown.

The case is the 102nd in the region. The person is now self-isolating.

This latest case comes just one day after the premier announced restrictions province-wide on social gatherings, just days after imposing these limits in the province’s current hot spots of Toronto, Ottawa and Peel Region.

Anyone who is a close contact of this latest case will be contacted by public health officials.

Take the COVID-19 self-assessment here

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CBC Windsor September 20 COVID-19 update: 9 new cases and new limits on gatherings – CBC.ca

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The Windsor-Essex County Health Unit reported nine new cases of COVID-19 in the region this weekend.

Six of the new cases are from people having close contact with confirmed cases, two of the cases were acquired in the community and one case is under investigation. 

There are 86 people with the virus currently in self isolation.

According to the health unit, 76 people have died because of the virus and 2,453 cases are resolved. 

As of Sunday, three senior facilities are considered to be in outbreaks, the most recent being Dolce Vita in Windsor which has had an outbreak since September 10. Four residents and two staff members have tested positive for COVID-19 at the facility.

Rosewood Erie Glen in Leamington had one staff member test positive for the virus. New Begninnings, also in Leamington, has had an outbreak since August 10 where 21 residents have tested positive along with seven staff members.

New gathering limits take hold 

On Saturday, the province of Ontario extended its limits on social gatherings to the entire province which were previously imposed in just the Toronto, Peel region and Ottawa areas. 

The decision comes following “alarming growth in the number of COVID-19 cases in the province.”

“Clearly, the numbers are heading in the wrong direction,” the premier said in a release. “We need everyone to follow the public health rules in order to prevent another province wide lockdown, and protect all our citizens, especially the elderly and the vulnerable.”

The limit on indoor gatherings was reduced from 50 people down to ten people, and only 25 people are allowed to gather outside rather than the previous limit of 100 people.

Ontario Premier Doug Ford extended new social gathering limits to the entire province on Saturday. (Chris Young/The Canadian Press)

The new limits, which were made effective immediately, will apply to functions such as, parties, dinners, gatherings, BBQs or wedding receptions held in private residences, backyards, parks and other recreational areas.

Organizers who hold such events face a minimum $10,000 fine.

The rules do not apply to “events or gatherings held in staffed businesses and facilities, such as bars, restaurants, cinemas, convention centres, banquet halls, gyms, places of worship, recreational sporting or performing art events.”

The limits are set to be in place for the next 28 days. 

Potential public exposures

Over the past few weeks, the health unit has flagged several businesses for potential COVID-19 exposures.

In each case, a customer or staff member has tested positive and the health unit wants anybody who may have come into contact to be alerted, self-monitor for symptoms and seek care if symptoms develop. 

The affected businesses and dates include:

  • The Chelsea at 576 Ouellette Ave. on Sept. 6
  • Spagos at 3850 Dougall Ave. on Sept. 6, Sept. 9, Sept. 10
  • Crunch Fitness LaSalle at 5844 Malden Rd. on Sept. 8.

COVID-19 in Sarnia-Lambton

Lambton Public Health has recorded a total of 344 cases of COVID-19.

Two cases are currently active and 317 are resolved.

Twenty-five people have died.

COVID-19 in Chatham-Kent

Chatham-Kent Public Health reported no new cases on Sunday. There have been a total of 366 positive cases, with three active cases in the community. 

Two of those cases are active and 362 people have recovered.

Two people have died from the virus in the region. 

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Nova Scotia reports no new coronavirus cases for 13th straight day – Global News

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Nova Scotia is reporting no new cases of the novel coronavirus for the 13th day in a row.

Sunday also marks the third day with no active cases of the virus in the province.

On Friday the province announced it is easing restrictions by increasing the gathering limit for organized sports and performing arts.

The number of people allowed to participate, including coaches, crew and anyone involved, is now 50.

Read more:
Nova Scotia eases COVID-19 regulations for organized activities

A news release says 858 negative tests were completed on Saturday, bringing the total number of tests completed since the pandemic began to 88,514.

To date, Nova Scotia has reported 1,086 active cases of COVID-19 and considers 1,021 cases resolved.

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There have been 65 deaths as a result of the virus in the province.






1:56
COVID-19 delayed opening of new YMCA in Halifax


COVID-19 delayed opening of new YMCA in Halifax

The province’s health officials urge anyone currently experiencing a fever or cough to visit the 811 website to see if an assessment is needed.

[ Sign up for our Health IQ newsletter for the latest coronavirus updates ]

In addition, if an individual is experiencing two or more of the following symptoms, they are also asked to see if an assessment is needed:

  • Sore throat
  • Runny nose
  • Headache
  • Shortness of breath

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Read more:
Here’s what you’ll need to do to enter each province in the Atlantic bubble

The Atlantic travel bubble remains operational.

The bubble permits interprovincial travel between Nova Scotia, New Brunswick, Prince Edward Island, and Newfoundland and Labrador without self-isolation.

However, restrictions will be in place. You can learn what you need to do ahead of time for each province here.

© 2020 Global News, a division of Corus Entertainment Inc.

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