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The billions of mRNA vaccine doses that went into arms worldwide during the COVID-19 pandemic build on clinical trial data confirming the safety and effectiveness of a vaccine technology now poised to personalize cancer treatment, according to a new review.
Dr. Manish Sadarangani, director of the Vaccine Evaluation Centre at B.C. Children’s Hospital, and his co-authors combed through published data from laboratory research, clinical trials and real-world surveillance from Pfizer-BioNTech’s and Moderna’s mRNA vaccines from January 2020 through December 2025 to assess their scientific and public health impacts.
In Tuesday’s issue of the medical journal The Lancet, the researchers highlighted one analysis showing mRNA vaccines had 87 per cent effectiveness against documented infection with the virus that causes COVID-19 and 94 per cent against mortality two to six weeks after vaccination. But the continual arrival of new viral variants means the effectiveness might change.
“We thought it was really important to have a resource where people can really understand what we know about this technology and what we know about these vaccines, where they have come from and where they may be going in the future,” Sadarangani told CBC News.
The mRNA vaccines built on decades of research that was quickly scaled up for regulators to approve, produce and distribute during the COVID pandemic.
COVID-19 vaccines have started rolling out across Canada for high-risk groups, but in Quebec and Alberta people will have to pay up to $180 for the shot this year.
Instead of using a weakened component of a live virus like a traditional vaccine, mRNA vaccines deliver a genetic code that acts as a set of instructions for our cells to make the virus’s spike protein. The spike protein is harmless on its own, but teaches our immune systems to recognize this foreign protein and learn to destroy it.
Put side-effects in context
One core finding, the study’s authors said, is that while heart-related inflammation called myocarditis and pericarditis are very rare side-effects of the mRNA vaccines, getting COVID itself puts people at far greater risk of the same heart issues.
The vaccine-associated heart events also tended to be more mild than ones from the virus, said Matthew Miller, a virologist and scientific director of the DeGroote Institute for Infectious Disease Research at McMaster University in Hamilton.
“It’s a signal we should watch out for,” Miller said, calling the information on heart-related side-effects useful and important. “But it’s also important to contextualize … the relative infrequency of that adverse event in relation to the clear, overarching benefit of vaccination.”
Miller, who was not involved in the Lancet review, called it a clear and concise summary of a large topic.
Looking back, Miller says much of the resistance in some pockets of the population to mRNA vaccines weren’t about the shots themselves, but likely reflected freedom of choice stances.
“It was this association of vaccines with being forced to be vaccinated rather than an inherent issue with the vaccine itself that led to I think to a lot of pushback,” he said.
If the public feels the medical and scientific establishment have been open and transparent about both the benefits of and adverse reactions to mRNA vaccines, then Miller says he thinks trust can be bolstered overall.
Pieter Cullis remembers giving a talk at Pfizer in March 2020, just days before Canada implemented stay-at-home measures to curb the deadly COVID-19 pandemic. Five years later, and after the mRNA vaccine technology he worked on found its way into billions of shots, he reflects on the role of nanoparticles in vaccines and how the cancer therapeutics he’s helping to develop are next.
Using mRNA technology to treat other diseases
The authors of the review also looked ahead to the future of mRNA in treating cancer and autoimmune diseases.
While vaccines teach the immune system to recognize and destroy pathogens, Miller said they can also teach the immune system to recognize and destroy tumours.
Dr. Ramy Saleh, an associate professor of oncology at Montreal’s McGill University, is part of a global randomized clinical trial evaluating an mRNA-based approach to treating bladder cancer.
The mRNA vaccines for cancer are custom built for each patient’s tumour, Saleh said.
First, surgeons remove the bladder cancer tumour. Next, scientists sequence it to find mutations specific to the tumour that aren’t found in the patient’s healthy DNA. Finally, a personalized mRNA therapy is given to prime the patient’s immune system to find and attack lingering cancer cells.
“The logic behind it is if our immune system knows that there are cancer cells and attacks them, the chances of a relapse or the cancer coming back will be much lower and the chances of a cure increase,” Saleh said.
