A newly released survey finds nearly all Canadian adults had antibodies against COVID-19 for about half of 2022, with most acquiring them through a previous infection.
The results, released Tuesday by Statistics Canada in partnership with the Public Health Agency of Canada and COVID-19 Immunity Task Force, show that 98.1 per cent of Canadian adults living in the country’s 10 provinces had antibodies against SARS-CoV-2, the virus that causes COVID-19, between April and August 2022.
These individuals acquired antibodies through either vaccination, previous infection or both.
Over that five-month period, 53.9 per cent developed antibodies through a past infection.
This is in comparison to the results of a previous version of the survey done between November 2020 and April 2021 that found 2.6 per cent of Canadians had COVID-19 antibodies due to a previous infection.
A report detailing the findings says while almost 54 per cent of Canadians surveyed had antibodies from an infection, the actual proportion of those infected since the start of the pandemic is likely higher.
“This is due, in part, to the fact that an antibody response to an infection may not always be detectable, especially among those who are vaccinated who may generate fewer antibodies following a subsequent infection. In addition, antibody levels can decrease over time,” the report says.
ANTIBODIES
The survey used a technique known as dried blood spot testing to detect COVID-19 antibodies from vaccination or a past infection, as well as saliva samples to determine a current or recent infection.
A total of 105,998 people were chosen to participate in the survey, of which 30.7 per cent completed a questionnaire asking about general health and exposure to COVID-19. Of those who completed the questionnaire, nearly 54 per cent provided a blood sample and 54.5 per cent provided a saliva sample.
The body produces antibodies to defend against diseases and in response to vaccination.
However, they do decrease over time and the report says some people previously infected with COVID-19 or who have been vaccinated may no longer have detectable levels of antibodies.
But while antibodies may decrease with time, the report says it does not mean a person’s immunity has waned.
Rather, an individual may have developed cell-mediated immunity, which activates specialized white-blood cells called T cells.
The report says dried blood spot testing also does not measure cell-mediated immunity.
Even without detectable antibodies, the report adds that cell-mediated immunity could be enough to protect someone against severe COVID-19 symptoms. The mere presence of antibodies alone also isn’t enough to suggest a person could fend off a new infection or any serious symptoms.
MANY UNAWARE THEY WERE INFECTED
The survey found as many as two out of five Canadians with antibodies from a previous infection were unaware they had been infected, either because they never tested positive or did not suspect an infection.
Among those who previously tested positive for COVID-19, antibody levels were higher between 14 and 90 days post-infection before gradually decreasing over time.
“While this is indicative of decreasing antibodies, there are other factors which could impact this analysis,” the report says.
“For example, since vaccines may lead to a lesser antibody response following an infection, the percentage of Canadians with antibodies from infection may be affected by changing vaccination rates over time. Further, since the survey focuses on first infections, re-infections would also impact this analysis as these could lead to a rebound in antibody levels.”
Canadians with a disability or underlying health conditions were less likely to have antibodies from a previous infection compared to those who did not report a disability or health condition.
Those 18-34 and 35-49 were also more likely to have antibodies from a previous infection than older Canadians were.
Antibody levels from infection varied between population groups, ranging from as low as 53 per cent for Chinese Canadians to as high as 80.7 per cent for Black Canadians.
Across provinces, Nova Scotia had the lowest proportion of residents who developed antibodies from infection at 46.5 per cent, while Quebec (56.5 per cent), Alberta (57.4 per cent) and Saskatchewan (57.4 per cent) had the highest rates.
The survey did not include data from the three territories, those under 18 or people living on reserve, in institutions or Canadian Forces Bases.
Some Ontario doctors have started offering a free shot that can protect babies from respiratory syncytial virus while Quebec will begin its immunization program next month.
The new shot called Nirsevimab gives babies antibodies that provide passive immunity to RSV, a major cause of serious lower respiratory tract infections for infants and seniors, which can cause bronchiolitis or pneumonia.
Ontario’s ministry of health says the shot is already available at some doctor’s offices in Ontario with the province’s remaining supply set to arrive by the end of the month.
Quebec will begin administering the shots on Nov. 4 to babies born in hospitals and delivery centers.
Parents in Quebec with babies under six months or those who are older but more vulnerable to infection can also book immunization appointments online.
The injection will be available in Nunavut and Yukon this fall and winter, though administration start dates have not yet been announced.
This report by The Canadian Press was first published Oct. 21, 2024.
-With files from Nicole Ireland
Canadian Press health coverage receives support through a partnership with the Canadian Medical Association. CP is solely responsible for this content.
ISLAMABAD (AP) — Polio cases are rising ahead of a new vaccination campaign in Pakistan, where violence targeting health workers and the police protecting them has hampered years of efforts toward making the country polio-free.
Since January, health officials have confirmed 39 new polio cases in Pakistan, compared to only six last year, said Anwarul Haq of the National Emergency Operation Center for Polio Eradication.
The new nationwide drive starts Oct. 28 with the aim to vaccinate at least 32 million children. “The whole purpose of these campaigns is to achieve the target of making Pakistan a polio-free state,” he said.
Pakistan regularly launches campaigns against polio despite attacks on the workers and police assigned to the inoculation drives. Militants falsely claim the vaccination campaigns are a Western conspiracy to sterilize children.
Most of the new polio cases were reported in the southwestern Balochistan and southern Sindh province, following by Khyber Pakhtunkhwa province and eastern Punjab province.
The locations are worrying authorities since previous cases were from the restive northwest bordering Afghanistan, where the Taliban government in September suddenly stopped a door-to-door vaccination campaign.
Afghanistan and Pakistan are the two countries in which the spread of the potentially fatal, paralyzing disease has never been stopped. Authorities in Pakistan have said that the Taliban’s decision will have major repercussions beyond the Afghan border, as people from both sides frequently travel to each other’s country.
The World Health Organization has confirmed 18 polio cases in Afghanistan this year, all but two in the south of the country. That’s up from six cases in 2023. Afghanistan used a house-to-house vaccination strategy this June for the first time in five years, a tactic that helped to reach the majority of children targeted, according to WHO.
Health officials in Pakistan say they want the both sides to conduct anti-polio drives simultaneously.
WASHINGTON (AP) — Millions of people with private health insurance would be able to pick up over-the-counter methods like condoms, the “morning after” pill and birth control pills for free under a new rule the White House proposed on Monday.
Right now, health insurers must cover the cost of prescribed contraception, including prescription birth control or even condoms that doctors have issued a prescription for. But the new rule would expand that coverage, allowing millions of people on private health insurance to pick up free condoms, birth control pills, or “morning after” pills from local storefronts without a prescription.
The proposal comes days before Election Day, as Vice President Kamala Harris affixes her presidential campaign to a promise of expanding women’s health care access in the wake of the U.S. Supreme Court’s decision to undo nationwide abortion rights two years ago. Harris has sought to craft a distinct contrast from her Republican challenger, Donald Trump, who appointed some of the judges who issued that ruling.
“The proposed rule we announce today would expand access to birth control at no additional cost for millions of consumers,” Health and Human Services Secretary Xavier Becerra said in a statement. “Bottom line: women should have control over their personal health care decisions. And issuers and providers have an obligation to comply with the law.”
The emergency contraceptives that people on private insurance would be able to access without costs include levonorgestrel, a pill that needs to be taken immediately after sex to prevent pregnancy and is more commonly known by the brand name “Plan B.”
Without a doctor’s prescription, women may pay as much as $50 for a pack of the pills. And women who delay buying the medication in order to get a doctor’s prescription could jeopardize the pill’s effectiveness, since it is most likely to prevent a pregnancy within 72 hours after sex.
If implemented, the new rule would also require insurers to fully bear the cost of the once-a-day Opill, a new over-the-counter birth control pill that the U.S. Food and Drug Administration approved last year. A one-month supply of the pills costs $20.
Federal mandates for private health insurance to cover contraceptive care were first introduced with the Affordable Care Act, which required plans to pick up the cost of FDA-approved birth control that had been prescribed by a doctor as a preventative service.
The proposed rule would not impact those on Medicaid, the insurance program for the poorest Americans. States are largely left to design their own rules around Medicaid coverage for contraception, and few cover over-the-counter methods like Plan B or condoms.
