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Contracting COVID-19 may provide some immunity. But still get vaccinated, scientists say – CBC.ca

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When it comes to acquired immunity against COVID-19, also known as natural immunity, scientists agree that people looking for protection against the coronavirus certainly shouldn’t be running out to get intentionally infected.

Yet a number of recent studies — some that suggest prior COVID-19 infection can provide significant immunity and others that suggest vaccination is much more effective — have triggered discussion within the scientific community about the strength of natural immunity.

Many scientists say vaccination is still essential for those who have contracted COVID-19, and that the combination of previous infection and vaccination may actually offer the best level of protection.

Monica Gandhi, a professor of medicine and infectious diseases at the University of California, San Francisco’s School of Medicine, is among the experts who believe one dose of vaccine after prior infection offers the best protection. She says the extent of immunity after infection is a very legitimate scientific debate.

“And the problem with this current debate,” she said, “is that to ignore natural immunity and say it isn’t a thing is leading to a lot of distrust of public health officials.”

‘Strongly disagree’ natural immunity better than vaccination

What goes beyond the bounds of legitimate debate, say many scientists, is the idea being suggested by some other scientists that acquired immunity from infection should be considered as effective or better than vaccination.

“I strongly disagree with that assessment,” said Theodora Hatziioannou, a virologist at the Rockefeller University in New York City.

Acquired immunity is the protection that a person develops to a disease after being infected. In Canada and the U.S., a previous infection is not counted as part of an individual’s vaccination status. A person who has had COVID-19 still requires two doses of an approved vaccine to be considered fully vaccinated.

But citizens in many European countries who have had the illness and received a single dose of vaccine are considered fully vaccinated. And in Israel, a person who has recovered from COVID-19 is considered fully vaccinated without having received a shot of vaccine.

In Canada and the U.S., a previous COVID-19 infection is not counted as part of an individual’s vaccination status. But citizens in many European countries who have had the illness and received a single dose of vaccine are considered fully vaccinated. (Evan Mitsui/CBC)

From a purely medical perspective, if someone has had a prior infection, they of course should be able to mount an immune response that can protect them for a certain amount of time, said Matthew Miller, an associate professor in the Michael G. DeGroote Institute for Infectious Diseases at McMaster University in Hamilton.

However, most of the studies that have compared the immunity resulting from infection with that of vaccination have found that two doses of vaccine, especially mRNA vaccines, provide higher levels of antibodies than a prior infection, he said.

Dawn Bowdish, Canada Research Chair in Aging and Immunity and a professor at McMaster University, said she’s been working with people who were hospitalized with COVID-19 and found they “tend to have pretty robust immune responses because they had quite a bit of time with the virus.”

She said immunity from previous infection may be enough for “some of the people, some of the time,” but it’s “quite proportionate to how sick you got, and there’s a lot of variability in people who had low-level infections.”

‘The durability of the response’

For example, Bowdish recently had someone give blood who had previously been infected with COVID-19 but only with very mild symptoms.

“We struggled to find any evidence that she had any immunity whatsoever,” Bowdish said of the test results.

When asked about natural immunity on CNN last month, Dr. Anthony Fauci, the top infectious disease expert in the U.S, said he couldn’t provide a firm answer on the subject. 

“That’s something that we’re going to have to discuss regarding the durability of the response,” said Fauci, director of the National Institute of Allergy and Infectious Diseases (NIAID).

It’s an issue many people opposed to vaccines have seized upon, particularly the comments of some scientists who have gone so far as to advocate natural immunity as equal to or perhaps better than double-dose vaccination.

The problem with that, says Hatziioannou, and what many scientists will point out, is that the level of natural immunity is quite varied between different people, and that protection varies depending on the severity of their prior illness.

As public officials continue to encourage Canadians to get vaccinated against COVID-19, plans are underway in many jurisdictions to expand the rollout of booster shots. (Jean-Claude Taliana/CBC/Radio-Canada)

Based on her own data, she estimates very few of those previously infected with COVID-19, around 10 per cent, mount a “really significantly high neutralizing antibody response.” 

The rest, she said, develop a medium to low response, with the majority pretty low.

“It appears the more sick you are, the higher the levels of your antibodies, generally speaking. But overall, the majority of infections are either asymptomatic or very, very mild to moderate. So I would not expect the majority of these people will have really high neutralizing antibodies.”

Impact on variants

As well, the particular coronavirus variant that infected the individual will inevitably have some degree of impact on how well it protects them from infection with a different variant, Miller said, which adds another layer of complexity to the issue.

“I think that the scientific issue of whether symptomatic infection can protect you from a future infection — I think that’s clear,” he said. “Is it clear exactly how well and to what extent and for what period of time? No, it’s not.”

Other scientists, meanwhile, suggest the case is pretty clear that natural immunity may provide more protection than previously thought.

Matthew Memoli, director of NIAID’s Laboratory of Infectious Diseases Clinical Studies Unit, told the BMJ, a U.K.-based peer-reviewed medical journal, that there probably isn’t much difference between natural immunity and vaccination in terms of resistance to the spike protein — a crucial feature on the surface of the coronavirus that allows it to gain access to our cells.

Vaccines, he said, are focused only on that tiny portion of immunity that can be induced by neutralizing the spike, while someone who has had COVID-19 was exposed to the whole virus, “which would likely offer a broader based immunity” that would be more protective against variants.

Experts make case for natural immunity

Jeffrey D. Klausner, a professor of population and public health sciences at the University of Southern California published a study that suggests there is “consistent epidemiological evidence” that prior infection provides “substantial immunity” to repeat infection and provides similar protection when compared to vaccination.

Marty Makary, a professor at the Johns Hopkins School of Medicine and Bloomberg School of Public Health in Baltimore, Md., has been very vocal in making his case that policy-makers need to consider natural immunity as equal to or better than vaccination.

Ideas53:58Dr. Anthony Fauci and the Problem with Science Skepticism

For over four decades, Dr. Anthony Fauci has served as medical advisor to seven U.S. presidents. With the COVID-19 death toll in the United States having surpassed 730,000, Dr. Anthony Fauci tells IDEAS host Nahlah Ayed that he finds it “mind-boggling” that partisanship and skepticism of science continue to fuel the pandemic. 53:58

In a Washington Post column last month, Makary, a surgical oncologist, wrote that for far too long, public health officials have dismissed natural immunity as unreliable protection against COVID-19 — “a contention that is being rapidly debunked by science.”

Makary pointed to some recent studies, including one in Israel that found people who were double vaccinated were six times more likely to get infected with the delta variant compared to those who had been previously infected with COVID-19 but not vaccinated.

But Fauci, during his appearance on CNN last month, said the Israeli study did not address the durability of immunity from infection compared to that which results from vaccination. 

“So you may be protected, but you may not be protected for an indefinite period of time,” he said.

Meanwhile, other studies have suggested limits to natural immunity. A study from the U.S. Centers for Disease Control and Prevention published last month found unvaccinated people previously infected with COVID-19 were twice as likely to be reinfected than those who were fully vaccinated after previously contracting the virus.

When asked about natural immunity on CNN last month, Dr. Anthony Fauci, the top infectious disease expert in the U.S, said one of the relatively unknown factors is how long it lasts. (Jeenah Moon/Getty Images)

Still, the efficacy of natural immunity could have potential policy implications, particularly in countries where vaccines are in short supply. 

And researchers are finding that the combination of prior COVID-19 infection and vaccination, so-called hybrid immunity, may offer the best protection. 

Bowdish said McMaster University is currently conducting a study in long-term care with 60 COVID-19 survivors. 

“And we definitely found that after they got their vaccine, they seem to be the ones that are having really robust, long immune responses,” she said.

Hatziioannou agreed that the research suggests people who were previously infected, even if their initial immune responses were not great, that once they get vaccinated, even with just with a single dose, their immunity “became remarkable.”

“It really is really great immunity,” she said. “It makes no sense to say that immunity from infections is sufficient.”

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Health Canada approves updated Moderna COVID-19 vaccine

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TORONTO – Health Canada has authorized Moderna’s updated COVID-19 vaccine that protects against currently circulating variants of the virus.

The mRNA vaccine, called Spikevax, has been reformulated to target the KP.2 subvariant of Omicron.

It will replace the previous version of the vaccine that was released a year ago, which targeted the XBB.1.5 subvariant of Omicron.

Health Canada recently asked provinces and territories to get rid of their older COVID-19 vaccines to ensure the most current vaccine will be used during this fall’s respiratory virus season.

Health Canada is also reviewing two other updated COVID-19 vaccines but has not yet authorized them.

They are Pfizer’s Comirnaty, which is also an mRNA vaccine, as well as Novavax’s protein-based vaccine.

This report by The Canadian Press was first published Sept. 17, 2024.

Canadian Press health coverage receives support through a partnership with the Canadian Medical Association. CP is solely responsible for this content.

The Canadian Press. All rights reserved.

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These people say they got listeria after drinking recalled plant-based milks

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TORONTO – Sanniah Jabeen holds a sonogram of the unborn baby she lost after contracting listeria last December. Beneath, it says “love at first sight.”

Jabeen says she believes she and her baby were poisoned by a listeria outbreak linked to some plant-based milks and wants answers. An investigation continues into the recall declared July 8 of several Silk and Great Value plant-based beverages.

“I don’t even have the words. I’m still processing that,” Jabeen says of her loss. She was 18 weeks pregnant when she went into preterm labour.

The first infection linked to the recall was traced back to August 2023. One year later on Aug. 12, 2024, the Public Health Agency of Canada said three people had died and 20 were infected.

The number of cases is likely much higher, says Lawrence Goodridge, Canada Research Chair in foodborne pathogen dynamics at the University of Guelph: “For every person known, generally speaking, there’s typically 20 to 25 or maybe 30 people that are unknown.”

The case count has remained unchanged over the last month, but the Public Health Agency of Canada says it won’t declare the outbreak over until early October because of listeria’s 70-day incubation period and the reporting delays that accompany it.

Danone Canada’s head of communications said in an email Wednesday that the company is still investigating the “root cause” of the outbreak, which has been linked to a production line at a Pickering, Ont., packaging facility.

Pregnant people, adults over 60, and those with weakened immune systems are most at risk of becoming sick with severe listeriosis. If the infection spreads to an unborn baby, Health Canada says it can cause miscarriage, stillbirth, premature birth or life-threatening illness in a newborn.

The Canadian Press spoke to 10 people, from the parents of a toddler to an 89-year-old senior, who say they became sick with listeria after drinking from cartons of plant-based milk stamped with the recalled product code. Here’s a look at some of their experiences.

Sanniah Jabeen, 32, Toronto

Jabeen says she regularly drank Silk oat and almond milk in smoothies while pregnant, and began vomiting seven times a day and shivering at night in December 2023. She had “the worst headache of (her) life” when she went to the emergency room on Dec. 15.

“I just wasn’t functioning like a normal human being,” Jabeen says.

Told she was dehydrated, Jabeen was given fluids and a blood test and sent home. Four days later, she returned to hospital.

“They told me that since you’re 18 weeks, there’s nothing you can do to save your baby,” says Jabeen, who moved to Toronto from Pakistan five years ago.

Jabeen later learned she had listeriosis and an autopsy revealed her baby was infected, too.

“It broke my heart to read that report because I was just imagining my baby drinking poisoned amniotic fluid inside of me. The womb is a place where your baby is supposed to be the safest,” Jabeen said.

Jabeen’s case is likely not included in PHAC’s count. Jabeen says she was called by Health Canada and asked what dairy and fresh produce she ate – foods more commonly associated with listeria – but not asked about plant-based beverages.

She’s pregnant again, and is due in several months. At first, she was scared to eat, not knowing what caused the infection during her last pregnancy.

“Ever since I learned about the almond, oat milk situation, I’ve been feeling a bit better knowing that it wasn’t something that I did. It was something else that caused it. It wasn’t my fault,” Jabeen said.

She’s since joined a proposed class action lawsuit launched by LPC Avocates against the manufacturers and sellers of Silk and Great Value plant-based beverages. The lawsuit has not yet been certified by a judge.

Natalie Grant and her seven year-old daughter, Bowmanville, Ont.

Natalie Grant says she was in a hospital waiting room when she saw a television news report about the recall. She wondered if the dark chocolate almond milk her daughter drank daily was contaminated.

She had brought the girl to hospital because she was vomiting every half hour, constantly on the toilet with diarrhea, and had severe pain in her abdomen.

“I’m definitely thinking that this is a pretty solid chance that she’s got listeria at this point because I knew she had all the symptoms,” Grant says of seeing the news report.

Once her daughter could hold fluids, they went home and Grant cross-checked the recalled product code – 7825 – with the one on her carton. They matched.

“I called the emerg and I said I’m pretty confident she’s been exposed,” Grant said. She was told to return to the hospital if her daughter’s symptoms worsened. An hour and a half later, her fever spiked, the vomiting returned, her face flushed and her energy plummeted.

Grant says they were sent to a hospital in Ajax, Ont. and stayed two weeks while her daughter received antibiotics four times a day until she was discharged July 23.

“Knowing that my little one was just so affected and how it affected us as a family alone, there’s a bitterness left behind,” Grant said. She’s also joined the proposed class action.

Thelma Feldman, 89, Toronto

Thelma Feldman says she regularly taught yoga to friends in her condo building before getting sickened by listeria on July 2. Now, she has a walker and her body aches. She has headaches and digestive problems.

“I’m kind of depressed,” she says.

“It’s caused me a lot of physical and emotional pain.”

Much of the early days of her illness are a blur. She knows she boarded an ambulance with profuse diarrhea on July 2 and spent five days at North York General Hospital. Afterwards, she remembers Health Canada officials entering her apartment and removing Silk almond milk from her fridge, and volunteers from a community organization giving her sponge baths.

“At my age, 89, I’m not a kid anymore and healing takes longer,” Feldman says.

“I don’t even feel like being with people. I just sit at home.”

Jasmine Jiles and three-year-old Max, Kahnawake Mohawk Territory, Que.

Jasmine Jiles says her three-year-old son Max came down with flu-like symptoms and cradled his ears in what she interpreted as a sign of pain, like the one pounding in her own head, around early July.

When Jiles heard about the recall soon after, she called Danone Canada, the plant-based milk manufacturer, to find out if their Silk coconut milk was in the contaminated batch. It was, she says.

“My son is very small, he’s very young, so I asked what we do in terms of overall monitoring and she said someone from the company would get in touch within 24 to 48 hours,” Jiles says from a First Nations reserve near Montreal.

“I never got a call back. I never got an email”

At home, her son’s fever broke after three days, but gas pains stuck with him, she says. It took a couple weeks for him to get back to normal.

“In hindsight, I should have taken him (to the hospital) but we just tried to see if we could nurse him at home because wait times are pretty extreme,” Jiles says, “and I don’t have child care at the moment.”

Joseph Desmond, 50, Sydney, N.S.

Joseph Desmond says he suffered a seizure and fell off his sofa on July 9. He went to the emergency room, where they ran an electroencephalogram (EEG) test, and then returned home. Within hours, he had a second seizure and went back to hospital.

His third seizure happened the next morning while walking to the nurse’s station.

In severe cases of listeriosis, bacteria can spread to the central nervous system and cause seizures, according to Health Canada.

“The last two months have really been a nightmare,” says Desmond, who has joined the proposed lawsuit.

When he returned home from the hospital, his daughter took a carton of Silk dark chocolate almond milk out of the fridge and asked if he had heard about the recall. By that point, Desmond says he was on his second two-litre carton after finishing the first in June.

“It was pretty scary. Terrifying. I honestly thought I was going to die.”

Cheryl McCombe, 63, Haliburton, Ont.

The morning after suffering a second episode of vomiting, feverish sweats and diarrhea in the middle of the night in early July, Cheryl McCombe scrolled through the news on her phone and came across the recall.

A few years earlier, McCombe says she started drinking plant-based milks because it seemed like a healthier choice to splash in her morning coffee. On June 30, she bought two cartons of Silk cashew almond milk.

“It was on the (recall) list. I thought, ‘Oh my God, I got listeria,’” McCombe says. She called her doctor’s office and visited an urgent care clinic hoping to get tested and confirm her suspicion, but she says, “I was basically shut down at the door.”

Public Health Ontario does not recommend listeria testing for infected individuals with mild symptoms unless they are at risk of developing severe illness, such as people who are immunocompromised, elderly, pregnant or newborn.

“No wonder they couldn’t connect the dots,” she adds, referencing that it took close to a year for public health officials to find the source of the outbreak.

“I am a woman in my 60s and sometimes these signs are of, you know, when you’re vomiting and things like that, it can be a sign in women of a bigger issue,” McCombe says. She was seeking confirmation that wasn’t the case.

Disappointed, with her stomach still feeling off, she says she decided to boost her gut health with probiotics. After a couple weeks she started to feel like herself.

But since then, McCombe says, “I’m back on Kawartha Dairy cream in my coffee.”

This report by The Canadian Press was first published Sept. 16, 2024.

Canadian Press health coverage receives support through a partnership with the Canadian Medical Association. CP is solely responsible for this content.

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B.C. mayors seek ‘immediate action’ from federal government on mental health crisis

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VANCOUVER – Mayors and other leaders from several British Columbia communities say the provincial and federal governments need to take “immediate action” to tackle mental health and public safety issues that have reached crisis levels.

Vancouver Mayor Ken Sim says it’s become “abundantly clear” that mental health and addiction issues and public safety have caused crises that are “gripping” Vancouver, and he and other politicians, First Nations leaders and law enforcement officials are pleading for federal and provincial help.

In a letter to Prime Minister Justin Trudeau and Premier David Eby, mayors say there are “three critical fronts” that require action including “mandatory care” for people with severe mental health and addiction issues.

The letter says senior governments also need to bring in “meaningful bail reform” for repeat offenders, and the federal government must improve policing at Metro Vancouver ports to stop illicit drugs from coming in and stolen vehicles from being exported.

Sim says the “current system” has failed British Columbians, and the number of people dealing with severe mental health and addiction issues due to lack of proper care has “reached a critical point.”

Vancouver Police Chief Adam Palmer says repeat violent offenders are too often released on bail due to a “revolving door of justice,” and a new approach is needed to deal with mentally ill people who “pose a serious and immediate danger to themselves and others.”

This report by The Canadian Press was first published Sept. 16, 2024

The Canadian Press. All rights reserved.

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