Health
SARS-CoV-2 Seroprevalence Grew Rapidly in Canada
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Editor’s note: Find the latest COVID-19 news and guidance in Medscape’s Coronavirus Resource Center.
By August 2022, 2½ years into the COVID-19 pandemic, most children and adults younger than 60 years had been vaccinated against SARS-CoV-2 or showed evidence of having been infected by the virus, new data suggest.
A Canadian seroprevalence study of almost 14,000 people found that fewer than 50% of people older than 60 years (the age group that is most vulnerable to severe outcomes) showed evidence of immunity from infection or had been vaccinated by August 2022. Older adults, who have the lowest infection rates but are at highest risk of severe outcomes, should continued to be prioritized for vaccination, according to the authors.
The data were published online December 5 in the Canadian Medical Association Journal.
Children Most Affected
Previous evidence suggests that a combination of infection and vaccination exposure may induce more robust and durable hybrid immunity than either infection or vaccination alone, study author Danuta Skowronski, MD, MHSc, an epidemiologist at the British Columbia Centre for Disease Control in Vancouver, told Medscape Medical News.
“Our main objective was to chronicle the changing proportion of the population considered immunologically naive and therefore susceptible to SARS-CoV-2,” she added. “It’s relevant for risk assessment to know what proportion has acquired some priming for more efficient immune memory response to the virus, because that reduces the likelihood of severe outcomes.” Standardized seroprevalence studies are essential for informing COVID-19 response, particularly in resource-limited regions.
The investigators analyzed anonymized residual sera from children and adults in an outpatient laboratory network in British Columbia’s Greater Vancouver and Fraser Valley region. They used at least three immunoassays per serosurvey to detect antibodies to SARS-CoV-2 spike (from vaccine) and to nucleocapsid antibodies (from infection).
The researchers determined any seroprevalence (vaccine-induced, infection-induced, or both) on the basis of a positive finding on any two assays. Infection-induced seroprevalence was also defined by dual-assay positivity but required both antinucleocapsid and antispike detection. Their estimates of infection-induced seroprevalence indicated considerable underascertainment of infections by standard case-based surveillance reports.
During the first year of the pandemic, when public health measures to curtail viral transmission were in place, the study population’s seroprevalence rate was less than 1% for the first three measurements. It was less than 5% by January 2021. With age-based vaccine rollouts, however, seroprevalence increased dramatically during the first half of 2021 to 56.2% by May–June 2021 and to 83% by September–October 2021. More than 85% of the population remained uninfected.
Infection-induced seroprevalence was less than 15% in September–October 2021 until the arrival of the Omicron waves, after which it rose to 42.5% by March 2022 and 61.1% by July–August 2022. Combined seroprevalence from vaccination or infection was more than 95% by the summer, with most children, but fewer than half of adults older than 60 years, showing evidence of having been infected.
“We found the highest infection rates among children, closely followed by young adults, which may reflect their greater interconnectedness, including between siblings and parents in the household, as well as with peers in schools and the community,” the authors write. They note that the low cumulative infection rates among older adults may reflect their higher vaccination rates and greater social isolation.
US data show similar age-related infection rates, but data among children from other Canadian provinces are limited, the authors write.
Broadly Applicable Findings
Commenting on the study for Medscape, Marc Germain, MD, PhD, vice president of medical affairs and innovation at Héma-Québec in Quebec City, said that the pattern observed in British Columbia is representative of what happened across Canada and the United States, including the sweeping effect of the Omicron variant and the differences in impact according to age. “But regional differences might very well exist — for example, due to differential vaccine uptake — and are also probably related in part to the different testing platforms being used,” he said. Germain was not involved in the study.
Caroline Quach-Thanh, MD, PhD, a pediatrician and epidemiologist-infectologist at the University of Montreal, pointed out that in Quebec, seroprevalence surveys that were based on residual blood samples from children and adults who visited emergency departments for any reason showed higher rates of prior infection than the British Columbia surveys. “But Dr Skowronski’s findings are likely applicable to settings where some nonpharmacological interventions were put in place, but without strict confinement — and thus are likely applicable to most settings in the US and Canada.” Quach-Thanh was not involved in the study.
She added that the use of residual blood samples always entails a risk for bias, “but the fact that the study method was stable should have captured a similar population from time to time. It would be unlikely to result in a major overestimation in the proportion of individuals positive for SARS-CoV-2 antibodies.”
A recent global meta-analysis found that while global seroprevalence rates have risen considerably, albeit variably by region, more than a third of the world’s population is still seronegative to the SARS-CoV-2 virus.
The Public Health Agency of Canada and the Michael Smith Foundation for Health Research provided funding for the study. Skowronski has received institutional grants from the Canadian Institutes of Health Research and the British Columbia Centre for Disease Control Foundation for Public Health for other SARS – CoV-2 work. Germain and Quach-Thanh have disclosed no relevant financial relationships.
CMAJ. Published online December 4, 2022. Full text
Diana Swift is a freelance medical journalist based in Toronto.
Health
We all experience stress. How we handle it is key to our health, say experts – CBC.ca
The Dose24:36What’s the connection between stress and my health and well-being?
It could be a morning traffic jam. A deadline at work. A conflict with a family member. Taking care of kids and aging parents.
Stressful situations are all around us, and experts say how we manage stress is key to preventing it from causing long-term health problems — both physical and mental.
Short-term stress doesn’t have to be negative, but research shows that ongoing stress wears away at the body’s systems and can lead to an increased risk of heart attack, stroke, Type 2 Diabetes, and mental health challenges.
“It’s like walking around with a ten or fifteen-pound weight continually on your back and not being able to shed that weight,” psychologist Dr. Zindel Segal told Dr. Brian Goldman, host of CBC’s The Dose.
There are techniques and strategies to decrease that stressful load, however, and lessen the impact of stress on the body and the mind.
Is stress good or bad?
Stress means that we are unable to use our personal or social resources to meet the demands being placed on us, said Dr. Eli Puterman, a health psychologist and associate professor in the school of kinesiology at UBC.
But not all stress is bad stress, said Puterman.
“It sometimes can motivate you to also move in the direction of, ‘Let’s change our goals,'” he said.
From an evolutionary perspective, our bodies are engineered to handle stress, said Segal, a distinguished professor of psychology and mood disorders at the University of Toronto Scarborough.
But after the stress response, we need a period of rest and recovery, which allows the body to recoup the resources that were used up during the stressful situation.
Chronic stress is when we’re unable to step out of the situation and take advantage of our own natural capacity to restore, said Segal.
It’s a system that is “stuck in the fifth gear without the ability to downshift,” he said.
Connecting with your senses
The first step to managing stress is recognizing it, said Segal, and that means tuning into our bodies.
“Are you noticing that maybe your heart is racing, or that your palms are sweating, or that your temple and forehead are pounding?” he said.
Grounding techniques can anchor us in the present moment and help pull us away from intrusive thoughts or feelings to take a broader view of the situation, said Segal.
“One of the things that we lose the ability to connect with is the sensory world,” he said, which is why so many techniques for managing stress are about reconnecting with your senses.
“Sensations are a way of actually helping us step out of thinking, to ground ourselves.”
A breath of fresh air
Doing yoga, meditating, exercising and deep breathing can all help ground us in our bodies and change our perspectives on stress, said Segal.
However, stress can cause barriers to being physically active, said Puterman, so he prefers to think about moving our bodies as opposed to exercising.
“Getting outside and going for some walks for 10, 15 minutes per day can help us start having those moments where we’re taking care of our bodies,” he said.
The Dose1:50A guided exercise in box breathing
One simple exercise Segal recommends is a technique called box breathing. Here’s how to try it:
- Sit in a chair and notice the sensations of sitting: the feet pressing down into the floor, the hands folded in the lap or on the thighs.
- Breathe in for four beats (visualize the left side of the box).
- Hold for four beats (visualize the top of the box).
- Breathe out for four beats (visualize the right side of the box).
- Hold for four beats (visualize the bottom of the box).
- Repeat as many times as you like.
What stress does to the body
It may be easy to understand how stress can take an emotional and mental toll, but research also shows that stress can have an impact on our physical health — including an increased risk of heart attack or stroke.
“In the short term, it rapidly increases your blood pressure, which can potentially result in a tear in the plaque that is in your arteries and then subsequently cause a heart attack or a stroke,” said Dr. Hassan Mir, a cardiologist at the Ottawa Heart Institute.
When we’re feeling stress, it activates our sympathetic nervous system, the part of our nervous system that carries signals related to our fight-or-flight response.
That can cause an increase in our blood pressure and heart rate, said Mir.
Another reaction to acute stress is a condition called takotsubo cardiomyopathy, or a weakened heart muscle, he said.
“When you’re really stressed, you can have this release of adrenaline in your body,” Mir said.
Mir has seen people who come into the hospital because their partner had a cardiac arrest, and then they suddenly get rushed to the ER because it looks like they’re having a heart attack.
“You go and look inside and the coronary arteries look completely fine, but their heart muscle looks like it’s completely weakened,” Mir said.
If you’re frequently activating your sympathetic nervous system due to stress, that can cause other issues in the body, said Puterman.
“If you’re starting to shift your baseline of the functioning of your physiology, you’re now entering the state where now you have too much cortisol that’s then activating too much glucose release,” he said.
Too much glucose released into the body can cause people to enter a pre-diabetes state, said Puterman.
How much stress is too much?
A little bit of stress could help us handle more stressful events in the future, a theory called the inoculation hypothesis, said Puterman.
“Some stress on a daily basis or in life actually inoculates you to future exposures to stressors,” he said.
But there are some telltale signs that the stress you’re experiencing is causing harmful effects, said Puterman. They include:
- Not sleeping well.
- Not getting as much exercise as usual.
- Consuming more alcohol or drugs.
- Withdrawing from others socially.
- Getting into more arguments with family or friends.
The trick is finding that sweet spot, said Segal, between having enough stress and too much.
“We don’t want to tip over into a point where the stress that we’re facing is overwhelming,” Segal said.
Health
Medical officer encourages measles vaccinations as global cases rise – SteinbachOnline.com
As cases of measles are increasing in parts of Canada and around the world, Manitobans are reminded that staying up to date on their vaccinations is one of the most important ways to prevent and reduce the risk of measles and other serious illnesses.
Measles is very contagious, says Dr. Mahmoud Khodaveisi, Medical Officer of Health for Southern Health-Santé Sud.
The most recognized symptom of measles is a red, blotchy rash, which often begins on the face and spreads down the body. Other common symptoms include fever, runny nose, cough, drowsiness, irritability and red eyes. Measles is a serious illness, especially for young children, and can result in lung and brain infections and other conditions that lead to serious complications or death.
Although there have been no recent confirmed cases of measles in our province since 2019, there is increasing concern as the number of cases are rising in Canada and around the world.
Dr. Khodaveisi says that before the vaccine was available, measles was a significant cause of childhood illness, and as a result, people born before 1970 are considered immune to measles as they were likely exposed growing up.
As part of Manitoba’s routine immunization schedule, children can receive two doses of a vaccine that protects against measles, first at 12 months and again between the ages of four and six. Together, these doses provide 97 per cent protection against measles.
The province reports that the most recent data available shows that about 80 per cent of children in Manitoba have received one dose of the vaccine that protects against measles by age two. Nearly 75 per cent of children have received two doses of the vaccine by age seven and this rate increases to over 88 per cent by the age of 17.
The province has sent information out about measles to health-care providers.
Measles is a reportable disease, meaning public health must be informed about cases by laboratories and health-care providers. Once a case is reported, public health will launch an investigation. This includes identifying close contacts, offering vaccination where appropriate and notifying the public of relevant exposures if needed.
Manitoba’s immunization registry was established in 1988, so records for anyone who has received immunizations since then should be contained in the registry.
If you are not sure if you or your children have been vaccinated, immunization records can be requested online at https://forms.gov.mb.ca/immunization-update-request/. Alternatively, you can contact your local public health office or contact your health-care provider.
-With files from Corny Rempel.
Health
Measles in Toronto: 2nd case confirmed
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A second lab-confirmed case of measles has been identified in Toronto.
The city’s public health agency said that an infant who recently returned from travel has contracted the disease. The child is recovering at home.
The first Toronto case was identified on Feb. 16.
Toronto Public Health is warning that anyone who attended the Agincourt Public Library between 1 p.m. and 5:30 p.m. on March 11 may have been exposed. Individuals should monitor for symptoms until April 1 and double check that their vaccinations are up to date.
Symptoms of measles include red rashes, fever, cough, runny nose, red eyes and fatigue. Individuals can also get unusual white spots in their mouth.
The number of measles infections in Ontario so far this year has already surpassed the total number of cases reported in 2023.
As of March 13, Public Health Ontario had confirmed at least eight cases of measles across the province. Cases have been identified in Peel Region, Hamilton, Brant County and Windsor-Essex County.
Of those infections, six were related to travel and two had an unknown source of exposure.
In 2023, there were seven cases of measles confirmed in Ontario.
Canada-wide data is less detailed, with the Public Health Agency of Canada reporting 17 cases of measles as of March 2, along with one case of congenital rubella syndrome.
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