The U.K.’s emergency approval of a Pfizer/BioNTech vaccine Wednesday may be the first step in ending our COVID-19 nightmare.
In the nine months since the World Health Organization declared a global pandemic, the speed of vaccine development – “the most highly regulated and monitored medical intervention that we have,” says Sneha Suresh, an assistant professor of pediatric immunology and infectious disease at the University of Alberta – has been unprecedented.
Significantly, it’s also the first time a messenger RNA (mRNA) vaccine has been approved for use, potentially revolutionizing vaccination. Moderna is close behind, with its mRNA vaccine awaiting regulatory approval. Both claim they are up to 95 per cent effective and are being reviewed by Health Canada.
Suresh says most vaccines are either inactivated (the virus or bacteria is inactivated by heat or chemicals) or live attenuated (a modified version of a virus or bacterium that can’t transmit the disease). Inactivated vaccines, such as the tetanus or flu vaccine, require multiple doses over time. Live attenuated ones, such as the measles, mumps and rubella vaccine, mimic a natural infection much better, and therefore require just one or two doses.
But the Pfizer/BioNTech and Moderna vaccines use mRNA and don’t require us to be injected with the virus. Instead, the vaccine contains instructions for our bodies to build a small protein normally found on the SARS-CoV-2 virus that causes COVID-19, thereby eliciting an immune response.
Occurring naturally in our bodies, mRNA works by taking information from our DNA and instructing our cells to build proteins we need to survive. These new vaccines harness this power by sending our body small bits of modified mRNA that tell it how to build a coronavirus protein.
Suresh likens our DNA to an encyclopedia with detailed instructions on how to build your entire body. But if you want to build just a hair cell, for example, you only need to consult a page in the book – and you definitely don’t want to carry the whole thing around.
“mRNA is like that photocopy. It’s not the exact encyclopedia. It’s just that one little piece,” she says. The photocopy gets translated into the protein and then the body gets rid of the mRNA fragment. Our DNA can’t make coronavirus proteins because it doesn’t have that information, so the vaccine gives our cells the instructions on how to do so by using modified mRNA.
Once our cells create the coronavirus protein, our immune system gets to work producing antibodies to the coronavirus and learning how to kill cells that may become infected by the virus. Suresh adds that there’s no risk to our DNA – mRNA from the vaccines basically does a quick in and out. She says mRNA vaccines are safe “because they don’t have much stability. They’re going to degrade pretty fast. There’s not a lot of risk of long-term side effects.”
So why haven’t we seen mRNA vaccines in the market already? “It’s just because it’s new technology,” she says. Despite being relatively easier to produce and costing less than traditional vaccines, scientists have had trouble bringing them to fruition since they started considering it as an option in the 1990s. This is mostly because our bodies’ defenses are actually quite good – they consider mRNA foreign and so tend to get rid of it before it reaches our cells. We effectively “shoot” the messenger.
The challenge to making this type of vaccine lies partly in finding the right dose of mRNA – not too small that it’s degraded by our bodies and not too large to throw the immune system out of whack – and finding the right adjuvant, or “delivery vehicle,” as Suresh calls it.
With so much to be done in such a short period of time, safety has been top of mind for everyone. “I don’t know if the general public knows how heavily monitored (vaccines are),” Suresh adds. Health Canada authorizes the vaccine for use in clinical trials, reviews the data and evidence to allow it to enter the market and continues monitoring the safety and efficacy of the vaccine once it’s in use. According to the Health Canada website, this process has been expedited by prioritizing treatments for COVID-19 without compromising patient safety.
Clinical trials show that some people do experience adverse effects (like fever or fatigue) from the vaccines, and Suresh knows that public confidence is key to people getting vaccinated. But she assures that the health sector will put this vaccine, like all others, under heavy surveillance.
mRNA vaccines could change what the future looks like for vaccines in general. Scientists have researched mRNA as a way to create stem cells in the human body to fight diseases like Parkinson’s or spinal cord injuries. It could also be used to create vaccines that could teach the body to destroy cancer cells through immunotherapy.
But that’s all down the line. COVID-19 is now the first priority.
“We’re dealing with a global pandemic that really has no end in sight,” Suresh says. “An effective vaccine will definitely help us in stemming the spread and decreasing deaths from it.”