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.
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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.”
The Canadian government says it will donate up to 200,000 vaccine doses to fight the mpox outbreak in Congo and other African countries.
It says the donated doses of Imvamune will come from Canada’s existing supply and will not affect the country’s preparedness for mpox cases in this country.
Minister of Health Mark Holland says the donation “will help to protect those in the most affected regions of Africa and will help prevent further spread of the virus.”
Dr. Madhukar Pai, Canada research chair in epidemiology and global health, says although the donation is welcome, it is a very small portion of the estimated 10 million vaccine doses needed to control the outbreak.
Vaccine donations from wealthier countries have only recently started arriving in Africa, almost a month after the World Health Organization declared the mpox outbreak a public health emergency of international concern.
A few days after the declaration in August, Global Affairs Canada announced a contribution of $1 million for mpox surveillance, diagnostic tools, research and community awareness in Africa.
On Thursday, the Africa Centres for Disease Control and Prevention said mpox is still on the rise and that testing rates are “insufficient” across the continent.
Jason Kindrachuk, Canada research chair in emerging viruses at the University of Manitoba, said donating vaccines, in addition to supporting surveillance and diagnostic tests, is “massively important.”
But Kindrachuk, who has worked on the ground in Congo during the epidemic, also said that the international response to the mpox outbreak is “better late than never (but) better never late.”
“It would have been fantastic for us globally to not be in this position by having provided doses a much, much longer time prior than when we are,” he said, noting that the outbreak of clade I mpox in Congo started in early 2023.
Clade II mpox, endemic in regions of West Africa, came to the world’s attention even earlier — in 2022 — as that strain of virus spread to other countries, including Canada.
Two doses are recommended for mpox vaccination, so the donation may only benefit 100,000 people, Pai said.
Pai questioned whether Canada is contributing enough, as the federal government hasn’t said what percentage of its mpox vaccine stockpile it is donating.
“Small donations are simply not going to help end this crisis. We need to show greater solidarity and support,” he said in an email.
“That is the biggest lesson from the COVID-19 pandemic — our collective safety is tied with that of other nations.”
This report by The Canadian Press was first published Sept. 13, 2024.
Canadian Press health coverage receives support through a partnership with the Canadian Medical Association. CP is solely responsible for this content.
HALIFAX – The Nova Scotia government says it could be months before it reveals how many people are on the wait-list for a family doctor.
The head of the province’s health authority told reporters Wednesday that the government won’t release updated data until the 160,000 people who were on the wait-list in June are contacted to verify whether they still need primary care.
Karen Oldfield said Nova Scotia Health is working on validating the primary care wait-list data before posting new numbers, and that work may take a matter of months. The most recent public wait-list figures are from June 1, when 160,234 people, or about 16 per cent of the population, were on it.
“It’s going to take time to make 160,000 calls,” Oldfield said. “We are not talking weeks, we are talking months.”
The interim CEO and president of Nova Scotia Health said people on the list are being asked where they live, whether they still need a family doctor, and to give an update on their health.
A spokesperson with the province’s Health Department says the government and its health authority are “working hard” to turn the wait-list registry into a useful tool, adding that the data will be shared once it is validated.
Nova Scotia’s NDP are calling on Premier Tim Houston to immediately release statistics on how many people are looking for a family doctor. On Tuesday, the NDP introduced a bill that would require the health minister to make the number public every month.
“It is unacceptable for the list to be more than three months out of date,” NDP Leader Claudia Chender said Tuesday.
Chender said releasing this data regularly is vital so Nova Scotians can track the government’s progress on its main 2021 campaign promise: fixing health care.
The number of people in need of a family doctor has more than doubled between the 2021 summer election campaign and June 2024. Since September 2021 about 300 doctors have been added to the provincial health system, the Health Department said.
“We’ll know if Tim Houston is keeping his 2021 election promise to fix health care when Nova Scotians are attached to primary care,” Chender said.
This report by The Canadian Press was first published Sept. 11, 2024.
ST. JOHN’S, N.L. – Newfoundland and Labrador‘s chief medical officer is monitoring the rise of whooping cough infections across the province as cases of the highly contagious disease continue to grow across Canada.
Dr. Janice Fitzgerald says that so far this year, the province has recorded 230 confirmed cases of the vaccine-preventable respiratory tract infection, also known as pertussis.
Late last month, Quebec reported more than 11,000 cases during the same time period, while Ontario counted 470 cases, well above the five-year average of 98. In Quebec, the majority of patients are between the ages of 10 and 14.
Meanwhile, New Brunswick has declared a whooping cough outbreak across the province. A total of 141 cases were reported by last month, exceeding the five-year average of 34.
The disease can lead to severe complications among vulnerable populations including infants, who are at the highest risk of suffering from complications like pneumonia and seizures. Symptoms may start with a runny nose, mild fever and cough, then progress to severe coughing accompanied by a distinctive “whooping” sound during inhalation.
“The public, especially pregnant people and those in close contact with infants, are encouraged to be aware of symptoms related to pertussis and to ensure vaccinations are up to date,” Newfoundland and Labrador’s Health Department said in a statement.
Whooping cough can be treated with antibiotics, but vaccination is the most effective way to control the spread of the disease. As a result, the province has expanded immunization efforts this school year. While booster doses are already offered in Grade 9, the vaccine is now being offered to Grade 8 students as well.
Public health officials say whooping cough is a cyclical disease that increases every two to five or six years.
Meanwhile, New Brunswick’s acting chief medical officer of health expects the current case count to get worse before tapering off.
A rise in whooping cough cases has also been reported in the United States and elsewhere. The Pan American Health Organization issued an alert in July encouraging countries to ramp up their surveillance and vaccination coverage.
This report by The Canadian Press was first published Sept. 10, 2024.
