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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.

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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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New technology to advance women’s cancer care at Southlake

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NEWS RELEASE
SOUTHLAKE REGIONAL HEALTH CENTRE
**************************
This Cancer Awareness Month, Southlake is adding advanced technologies to detect and treat breast cancer and other women’s cancers thanks to generous community donor support, most recently through the HERE is Where Cancer Meets its Match campaign. New cancer care technology, including new mammography machines, the MyoSure System and the MOLLI 2® System will make a measurable impact in diagnosing and treating women’s cancers in the communities Southlake serves.

Southlake is installing three new mammography machines to expand its breast cancer screening program to 1,500 more women each year. Two of these machines have new biopsy capabilities that will reduce the number of cancelled exams due to equipment failure, ensuring timely care for women. Women ages 40 to 49 years old will be able to self-refer for publicly funded mammograms through the Ontario Breast Screening Program starting this fall.

“Early detection is critical when treating breast cancer and other women’s cancers,” said Lorrie Reynolds, Director, Regional Cancer Program at Southlake. “We treat more than 1,700 breast cancer patients at Southlake every year. By adding advanced technology, like the new mammography machines, we’re ensuring women have the best experience at Southlake.”

Southlake is also introducing the MyoSure System, an innovative technology that can help detect female reproductive cancers. Damaged tissue in a woman’s uterus such as fibroids and polyps can now be removed in a precise, minimally invasive procedure that leaves the rest of the uterus intact. This will improve the overall patient experience by supporting faster recovery, reducing the risk of infection and giving more women the option to have children. An estimated 200 women per year will benefit from the MyoSure System.

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The new mammography machines and the MyoSure System build on Southlake’s recent investment in the MOLLI 2® System, a made-in-Canada wire-free breast localization technology.  This technology is considerably less invasive and more accurate when compared to wire-guided localization, resulting in a better patient experience and improved cosmetic outcomes.  More than 200 women each year will benefit from this innovative medical device as they are treated for breast cancer at Southlake.

“As a clinician caring for women with cancer in our community, I’m incredibly proud of the work Southlake is doing to advance women’s health and improve patient experiences,” said Sara Temple, MD, Surgical Oncologist and Chief of Surgery at Southlake. “Women who visit Southlake can be confident that they are receiving leading edge care, close to home when they need it most.”

The World Health Organization anticipates a 77 per cent increase in cancer diagnoses by 2050.  Southlake serves some of the fastest growing communities in Canada and anticipates that the number of patients requiring cancer care will grow. By investing in new technology, Southlake is ensuring that women in the communities it serves have access to leading edge cancer care. All of these investments were funded with support from community donors who generously gave to Southlake to support investments into women’s health at the hospital.

“The generosity of our donor community and the impact they have made for women receiving cancer diagnosis and treatment at Southlake is something we can all take great pride in,” said Jennifer Ritter, President and CEO of Southlake Foundation. “From our Women’s Health Initiative donors supporting new mammography machines, to the Ladies in Philanthropy for Southlake funding the MOLLI 2 System, to our long-standing partners The Edge Benefits and Pheasant Run Golf Club enabling the introduction of MyoSure System through their joint annual charity golf tournament, we are incredibly lucky to share a vision of access to exceptional care for everyone who depends on Southlake when they need us most. Thank you, to every donor who contributed to these important upgrades to care for women.”

Southlake Foundation’s HERE is Where Cancer Meets its Match campaign supports the Stronach Regional Cancer Centre at Southlake. For more information or to make a donation, visit: southlake.ca/HERE.

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Pasteurized milk includes remnants of H5N1 bird flu, U.S. officials say

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The U.S. Food and Drug Administration says that samples of pasteurized milk have tested positive for remnants of the bird flu virus that has infected dairy cows.

The agency stressed that the material is inactivated and that the findings “do not represent actual virus that may be a risk to consumers.” Officials added that they’re continuing to study the issue.

“To date, we have seen nothing that would change our assessment that the commercial milk supply is safe,” the FDA said in a statement on Tuesday.

The announcement comes nearly a month after an avian influenza virus that has sickened millions of wild and commercial birds in recent years was detected in dairy cows in at least eight states. The Agriculture Department (USDA) says 33 herds have been affected to date.

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FDA officials didn’t indicate how many samples they tested or where they were obtained. The agency has been evaluating milk during processing and from grocery stores, officials said. Results of additional tests are expected in “the next few days to weeks.”

WATCH | Bird flu spread in U.S. cows:

 

Bird flu is spreading in cows. Are humans at risk? | About That

15 days ago

Duration 8:54

For the first time ever, avian influenza, or H5N1 bird flu, was detected in roughly a dozen dairy cow herds across the U.S. About That producer Lauren Bird explores why scientists and public health officials are concerned about the cross-species transmission and whether humans are now at higher risk.

The polymerase chain reaction (PCR) lab test the FDA used would have detected viral genetic material even after live virus was killed by pasteurization, or heat treatment, said Lee-Ann Jaykus, an emeritus food microbiologist and virologist at North Carolina State University

“There is no evidence to date that this is infectious virus, and the FDA is following up on that,” Jaykus said.

Officials with the FDA and the USDA had previously said milk from affected cattle did not enter the commercial supply. Milk from sick animals is supposed to be diverted and destroyed. Federal regulations require milk that enters interstate commerce to be pasteurized.

Tests for viable virus underway, agency says

Because the detection of the bird flu virus known as Type A H5N1 in dairy cattle is new and the situation is evolving, no studies on the effects of pasteurization on the virus have been completed, FDA officials said. But past research shows that pasteurization is “very likely” to inactivate heat-sensitive viruses like H5N1, the agency added.

The agency said it has been evaluating milk from affected animals, in the processing system and on the shelves. It said it is completing a large, representative national sample to understand the extent of the findings.

The FDA said it is further assessing any positive findings through egg inoculation tests, which it described as a gold standard for determining viable virus.

Matt Herrick, a spokesperson for the International Dairy Foods Association, said that time and temperature regulations for pasteurization ensure that the commercial U.S. milk supply is safe. Remnants of the virus “have zero impact on human health,” he wrote in an email.

Scientists confirmed the H5N1 virus in dairy cows in March after weeks of reports that cows in Texas were suffering from a mysterious malady. The cows were lethargic and saw a dramatic reduction in milk production. Although the H5N1 virus is lethal to commercial poultry, most infected cattle seem to recover within two weeks, experts said.

To date, two people in the U.S. have been infected with bird flu. A Texas dairy worker who was in close contact with an infected cow recently developed a mild eye infection and has recovered. In 2022, a prison inmate in a work program caught it while killing infected birds at a Colorado poultry farm. His only symptom was fatigue, and he recovered.


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Remnants of bird flu virus found in pasteurized milk, FDA says

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The U.S. Food and Drug Administration said Tuesday that samples of pasteurized milk had tested positive for remnants of the bird flu virus that has infected dairy cows.

The agency stressed that the material is inactivated and that the findings “do not represent actual virus that may be a risk to consumers.” Officials added that they’re continuing to study the issue.

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