Health
Do we know how effective vaccines are against the variants?  Answers to your questions about COVID-19

Do we know how effective vaccines are against the variants? Answers to your questions about COVID-19

We answer your questions about the pandemic. Send yours to COVID@cbc.ca, and we’ll get back to you as much as possible. We post a selection of responses online and also ask questions of experts on National and on CBC News Network. So far, we have received over 67,000 emails from across the country.


Are the vaccines effective against all of the variants of concern?

Pfizer-BioNTech and Moderna say their COVID-19 vaccines appear to be effective against two worrisome variants first identified in the UK and South Africa, based on blood samples from people who have been vaccinated. But more research is needed on the pair of vaccines, while other vaccine candidates already have real data on their effectiveness against the variants.

The good news is that the coronavirus that causes COVID-19 does not appear to mutate as much or as quickly as the influenza virus that causes the flu. Even with the current worrisome, more transmissible variants, people who have been vaccinated do not get seriously ill or die from COVID-19 in large numbers.

But to prepare for in case this starts to happen, drugmakers are already reworking their vaccines.

Phil Dormitzer, one of Pfizer’s top viral vaccine scientists, said last week that his company had already created a model for a prototype vaccine targeting the variant first identified in South Africa.

Retooling work took on new urgency after South Africa suspended deployment AstraZeneca vaccine after data from a small trial suggested the vaccine did not protect against mild to moderate disease of the now dominant B1351 variant in the country.

Despite this, Dr Zain Chagla, an infectious disease specialist at St. Joseph’s Healthcare in Hamilton, Ont., Told CBC’s Dr Brian Goldman The dose let him remain optimistic that existing vaccines can fight the coronavirus variants. That’s because five different vaccines have been submitted to Health Canada for approval, Chagla said, and each may play a role in controlling variants.

“The best vaccine is the one that is administered,” Chagla said. “All Canadians should be hoping that they can get one of these vaccines, period.

Moderna and Pfizer-BioNTech clinical trials were completed before the worrisome variants took off worldwide.

Dr Noni MacDonald, professor of pediatrics at Dalhousie University in Halfax and vaccine safety researcher, said that as experts gain a more detailed and sophisticated perspective on how COVID-19 vaccines work, they will also gain a better understanding of the types of protection they offer.

Studies suggest that the AstraZeneca vaccine is not very effective against the variant first identified in South Africa. Do we know how effective other vaccines are against this?

Yes, we have information on other vaccines.

So far, three drug makers – Johnson & Johnson, Oxford-AstraZeneca and Novavax – have data comparing the effectiveness of their vaccines against the B1351 variant first identified in South Africa.

The variant has a mutation that changes the shape of the viral spike protein.

As a result, laboratory experiments suggest that the antibodies our bodies produce have a harder time attaching to the spike protein, which reduces the effectiveness of vaccines. say virologists.

But infectious disease experts say vaccines could still save lives in the middle of B1351 housings by preventing intensive care admissions of severe COVID-19, reducing the strain on our health care systems – the goal of flattening the curve.

WATCH | Re-tool vaccines to monitor coronavirus variants:

New coronavirus variants won’t necessarily mean new vaccines or vaccine boosters are needed. And if adjustments are necessary, their development would take less time than the original vaccines. 2:01

Preliminary data of Johnson & Johnson’s single-dose vaccine suggested it was 72% effective against moderate to severe COVID-19 in the United States, compared to 57% in South Africa, where a more contagious variant was circulating at the time of the outbreak. research.

The Novavax vaccine has also shown some protection against the B1351 variant, said Dr. Isaac Bogoch, an infectious disease specialist at the University of Toronto Health Network.

In a press release, Novavax said that his vaccine’s effectiveness in studies conducted in the UK was 89 percent compared to 60 percent in South Africa.

Protection can include not getting the infection as well as protection against serious infection, hospitalization and death.

“So while it’s not perfect, even if it’s not the same, Johnson & Johnson, Novavax and quite possibly Pfizer and Moderna still provide an element of protection against this worrisome variant,” Bogoch said, who is also a member of the Ontario COVID-19 Vaccine Distribution Working Group.

We hear the variant first identified in the UK may be deadlier. Does it apply to all age groups?

“Based on the limited evidence we have, this appears to apply to all age groups,” Maria Sundaram, a Toronto-based infectious disease epidemiologist, told CBC News Network.

In January, British Prime Minister Boris Johnson declared two studies presented to his government suggested that the B117 variant “may be associated with a higher degree of mortality. “

Patrick Vallance, Johnson’s chief scientific adviser, said the previous average death rate of 60-year-olds in the UK from COVID-19 was around 10 per 1,000. With the new variant, we can expect about 13 or 14 per 1,000 infected people die.

The relative increase in case fatality rate “appears to be apparent in all age groups,” the researchers wrote. “The absolute risk of death from infection remains low.”

Do you think we will need boosters to protect you from the variants even after receiving both doses of a vaccine?

The answer is yes, says Bogoch.

For the first generation of COVID-19 vaccines, Bogoch said he expects people to eventually need a booster dose.

“Down the line, and I don’t know how much further down we would probably need a booster dose with an updated vaccine or vaccine that explains the new worrisome variants that are emerging,” he said. he declares.

A healthcare worker is seen at a COVID-19 testing center at Ridge Meadows Hospital in Maple Ridge, British Columbia, earlier this month after a case of the variant coronavirus was detected in a nearby secondary school. (Ben Nelms / CBC)

MacDonald said major regulatory bodies such as Health Canada, the United States Food and Drug Administration and their counterparts in the United Kingdom and Europe are meeting virtually to discuss how to assess the effectiveness of vaccines against the variants.

She said regulators could ask drugmakers for so-called non-inferiority studies.

Unlike clinical trials to assess the effectiveness of a vaccine that involve 40,000 to 50,000 people, MacDonald said non-inferiority trials require 400 to 500 people and can be done relatively quickly.

“We will do non-inferiority,” MacDonald said. “It’s a simpler and easier process and you just have to say, ‘Are you good if not better than what you had before?'”

Alyson Kelvin, a virologist working on COVID-19 vaccine candidates at VIDO-InterVac in Saskatoon, said surveillance in Canada and around the world will be important to see which variants people are commonly infected, both in vaccinated populations and unvaccinated.

“I am optimistic that we will always have effective vaccines and that we will not go into a cycle of vaccination and changing vaccine formulations as frequently as we do with the flu,” Kelvin said.

A lab technician works on blood samples taken from people participating in a Johnson & Johnson COVID-19 vaccine study in Groblersdal, South Africa, northeast of Johannesburg on February 11. The five different vaccines submitted to Health Canada for approval may each play a role in variant control. (Jerome Delay / Associated Press)

When a person is infected with the original version of the virus and develops antibodies, these antibodies have been shown to be less effective against some new variants of concern with modified spike proteins.

Researchers have documented cases of reinfection with the variant identified for the first time Manaus, Brazil. But re-infections are difficult to prove because doctors need genetic evidence showing that a separate strain of coronavirus caused each instance of infection.

Our body makes antibodies to fight off a natural infection. Besides antibody based immunity, our immune system also has T cell immunity or cell based immunity. T cells are a type of white blood cell.

Kelvin said cellular immunity is often broader than what we get from antibodies alone.

Immunologists say antibody are also relatively short-lived compared to some T cells.

Kelvin said it would be important for researchers to watch for any breakthrough infection of a variant suggesting that both arms of immunity are no longer effective.

Alyson Kelvin, who is working on different coronavirus vaccine candidates, is seen in his VIDO-InterVac lab in Saskatoon last March. She says she is optimistic that we will always have effective vaccines against the variants. (Liam Richards / The Canadian Press)

Brian Lichty of the McMaster Immunology Research Center in Hamilton, who is also working on COVID-19 vaccine candidates, said the variant genes could be swapped out for an existing mRNA vaccine, such as those made by Pfizer-BioNTech and Moderna.

“Technically, it’s really simple,” Lichty said. “I can, with my laptop, design a new vaccine in 20 minutes sitting on my couch.”

Then, in the laboratory, the new gene is synthesized. Finally, the new vaccine is mass-produced – the most time-consuming step, he said.

Looking ahead, drugmaker GlaxoSmithKline (GSK) has said it will work with the German pharmaceutical company Curevac to develop an mRNA vaccine against the variants.

The advantage of existing mRNA vaccines from Pfizer-BioNtech and Moderna over vaccines based on older technologies do they don’t need cells or tissue cultures to grow. This is one of the reasons it is easier to change recipes in their manufacturing lines to process variations, MacDonald said.

Leave a Reply

Your email address will not be published. Required fields are marked *