We’re answering your questions about the pandemic. Send them to COVID@cbc.ca, and we’ll answer as many as we can. We publish a selection of answers online and also put some questions to the experts during The National and on CBC News Network. So far, we’ve received more than 59,000 emails from all corners of the country.
As the first coronavirus shots got into arms across Canada, CBC News talked to the experts to answer your questions about how the vaccines got to this stage, such as: What does “90 per cent efficacy” mean in a clinical trial? And what kinds of volunteers have been in clinical trials or excluded?
What is the effect of mRNA vaccines on DNA? Is it true that it alters DNA?
The mRNA vaccines like those developed by Pfizer-BioNTech and Moderna don’t use DNA.
RNA is like a temporary photocopy of DNA and is used to make proteins. Proteins are the building blocks that cells used to grow and repair themselves. Once the protein is made, the RNA is degraded.
“In humans, the progression is always DNA to RNA to protein,” said Dr. Zain Chagla, an associate professor of medicine at McMaster University and an infectious disease physician in Hamilton, Ont.
“You can’t go from RNA back to DNA in human cells. It’s not possible because we just don’t have the machinery to deal with it. So there should not be concerns about the RNA vaccine somehow getting into the human DNA and transforming it.”
There is one kind of microbe that can produce DNA from RNA — retroviruses such as HIV. And the DNA generated by retroviruses can sometimes integrate into cells, Matthew Miller, an associate professor of infectious diseases and immunology at McMaster University, said in an email.
Miller said that RNA from retroviruses is structurally different from mRNA.
“So even if one was infected with a retrovirus, the mRNA in the vaccine would not alter our DNA.”
Jason Kindrachuk, Canada Research Chair in molecular pathogenesis of emerging and re-emerging viruses at the University of Manitoba, also thinks the risk of integration is tiny. The amount of mRNA in the vaccine is far lower than the amount generated in a natural infection, he noted in an email, and trials of either this type of COVID-19 vaccine or mRNA vaccines under development for other diseases have shown no indications that integration could be a risk. He added there are no noted contraindications for people with HIV on the product monograph, and the only thing it says about immunocompromised patients is that they could have a diminished immune response.
If participants in Phase 3 clinical trials are not intentionally exposed to the virus, how can vaccine efficacy be calculated?
People in the clinical trials were divided into two groups — those who got the vaccine and those who got a dummy shot. They would have gone to work and school and had social interactions as they normally do. Because Phase 3 clinical trials were mostly done in places with very active pandemics, such as the U.S. and Brazil, a certain number of participants would have been exposed to the virus that causes COVID-19 in their daily lives.
Efficacy was calculated by comparing the number of infections among those who got the vaccine and those who got the dummy shot.
Efficacy is how well the vaccine works in clinical trials. Effectiveness is how well a vaccine or a product will work in real world settings.
How do we interpret “90% efficacy” of a vaccine in a clinical trial? Does this mean 90 out of 100 people will have immunity to the virus?
No. The clinical trials so far generally weren’t designed to measure whether people were immune to the virus. They were designed to see whether it reduced their chances of getting symptomatic disease. Ninety per cent efficacy means those who got the vaccine were 90 per cent less likely to get symptomatic COVID-19 than those who got the dummy shot.
WATCH | Vaccines a light at the end of a long tunnel, WHO says:
As vaccinations get underway, the World Health Organization’s technical lead, Maria Van Kerkhove, makes an impassioned appeal for people to protect themselves and loved ones from COVID-19 in 2021. 1:48
However, the trials did not generally test for asymptomatic infection, so it’s not clear how many people actually had immunity to infection.
What kinds of volunteers have been in clinical trials and who has been excluded so far? From an efficiency point of view, can a vaccine protect different persons differently?
Both Pfizer-BioNTech and Moderna said the efficacy of their vaccines was consistent across age, race and ethnicity, and gender demographics. Pfizer-BioNTech also specified the vaccine was 94 per cent effective in adults older than 65.
(CBC)
Neither company reported results specifically for people with chronic conditions.
Chagla said as the vaccine rolls out to millions of people worldwide, we’ll learn more about people in different age groups or who have other illnesses.
“We’ll get a better sense of whether or not this vaccine does prevent people from transmitting and shedding COVID-19 or just makes their symptoms much better and are still transmissible,” Chagla said.
Dr. Joanne Langley, a pediatric infectious disease specialist in Halifax who co-leads Canada’s vaccine task force, said companies are planning trials in children and in pregnant women, which are expected to start in this country in 2021. International trials are also expanding to include children under the age of 16, vaccine makers say.
Do we know if the Pfizer-BioNTech vaccine is safe for pregnant women, breastfeeding women and children?
So far, there isn’t any specific data on pregnant and breastfeeding women, so vaccine makers can’t say for sure whether the vaccine is safe for that group or not.
However, Dr. Michael Gardam, a Toronto infectious disease physician who is the senior medical advisor for Health PEI, said: “There’s nothing about this vaccine that would suggest that it would cause any problems in pregnant women.” Pregnant women will likely have the option to receive the vaccine.
Biotechnology company Moderna protocol files for COVID-19 vaccinations sit in binders at the Research Centers of America in Hollywood, Florida, in August. The mRNA vaccines like PFizer-BioNtech and Moderna’s don’t use DNA. (Chandan Khanna/AFP via Getty Images)
Gardam recommends talking to your doctor about it.
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.
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