Health and Medicine
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Billions of doses later, a global review has found that mRNA vaccines are safe and highly effective. Not only have they proven to be a valuable weapon against COVID-19, it reports, but the platform shows promise for treating many other diseases, including influenza, RSV, autoimmune disorders, and even cancer.
The rest of this article is behind a paywall. Please sign in or subscribe to access the full content.The first mRNA vaccines approved for widespread human use were the Pfizer-BioNTech and Moderna vaccines against COVID-19 in 2020 and 2021. While their rollout was lambasted as "rushed" by some, research into the technology had really been decades in the making.
Now that billions upon billions of doses have been administered around the globe, scientists can take a step back and get a clear view of their impact, resulting in a new global review.
“After billions of doses, we now have an extraordinary amount of scientific evidence,” Anna Blakney, assistant professor at the University of British Columbia, said in a statement.
“People should feel empowered to ask questions about their health and what they put in their bodies,” said Blakney. “Our goal is to provide clear, credible evidence to inform these conversations and decisions.”
What did the review find?
The researchers compiled and assessed heaps of mRNA vaccine data from around the world taken from laboratory research, clinical trials, and real-world surveillance.
Serious adverse side effects from mRNA vaccines were exceptionally rare, with myocarditis and pericarditis (inflammation of the heart) occurring in just 12.6 cases per million for Pfizer BioNTech's COVID-19 vaccine and 35.6 cases per million for Moderna’s COVID-19 vaccine. Both values are substantially lower than the risk of getting those conditions from a COVID-19 infection.
The risk of anaphylaxis following Pfizer BioNTech's COVID mRNA vaccine was 4.7 cases per million doses, and Guillain-Barré syndrome risk after the AstraZeneca vaccine was 38 cases per million doses. The majority of other side effects were mild – such as sore arms, fatigue, or fever – and only lasted a few days.
The review also found mRNA vaccines to be effective at preventing serious COVID-19 infections, with 87 percent overall effectiveness against SARS‑CoV‑2 infection, 93 percent effectiveness against hospitalization, and 94 percent effectiveness against mortality 14 to 42 days after vaccination.
Effectiveness waned over time, however, and was reduced by certain variants, such as the Omicron lineage (for which the vaccines on the whole had 67 percent effectiveness against infection and 72 percent against hospitalization).
The team also addressed some common misconceptions about how mRNA vaccines work. Above all, they sought to clarify that these medications don't alter a person's DNA. Instead, the mRNA provides a set of instructions that prompts human cells to produce a harmless piece of a virus, training the immune system to recognize and respond to it.
Both the mRNA and the lipid nanoparticles it's packaged within are quickly broken down and cleared from the body after use.
The findings also support mRNA technology's potential for treating diseases beyond COVID-19. An ever-expanding list of trials – for everything from pancreatic cancer to bird flu – are already underway, potentially meaning that we will have mRNA vaccines for a wide range of illnesses in the near future.
“This is really about what comes next,” said Blakney. “We’re seeing the same platform being applied to cancer treatment and other diseases. Understanding how these vaccines work—and why they’re safe—helps build confidence in the next generation of medicines.”
The study is published in the journal The Lancet.
