The researchers concluded that the benefits of mRNA vaccines greatly outweigh the risks, even for groups such as children, pregnant women and people with weakened immune systems.
Messenger RNA (mRNA) vaccines are one of the biggest medical breakthroughs of recent years. It was first introduced during the Covid-19 pandemic and they helped protect millions of people from severe illness in a short period of time. Since then, scientists have continued to study these vaccines in detail. A new review published in The Lancet has now examined data from billions of administered doses and confirmed that mRNA vaccines are both safe and highly effective against infectious diseases. These findings highlight the role of mRNA vaccines in modern healthcare.
The review was conducted by researchers from the University of British Columbia in Canada and the London School of Hygiene and Tropical Medicine, and other institutions. The researchers concluded that the benefits of mRNA vaccines greatly outweigh the risks, even for groups such as children, pregnant women and people with weakened immune systems. They also believe the technology has the potential to protect against many other diseases in the future.
How mRNA Vaccines Work
Unlike traditional vaccines, mRNA vaccines do not contain a weakened or inactive virus. Instead, they carry temporary genetic instructions that tell human cells to produce a harmless protein found on a virus. This harmless protein teaches the immune system to recognise the virus and prepare a defence against it.
So, when the real virus enters the body later, the immune system can respond quickly and effectively. The mRNA itself does not enter the cell’s nucleus or change a person’s DNA. After delivering its instructions, it naturally breaks down and is removed from the body.
Evidence of Safety and Effectiveness
The review analysed billions of vaccine doses given around the world. Researchers found that these vaccines provide strong protection against severe Covid-19 and other infectious diseases across different age groups and health conditions.
The evidence also confirmed that mRNA vaccines are effective for children, pregnant women and people with compromised immune systems. Booster doses were shown to improve and extend protection, especially as new virus variants appeared. This combination of clinical trials and real-world monitoring gives scientists a high level of confidence in the vaccines’ performance.
Anna Blakney, assistant professor at the University of British Columbia and lead author, said, “After billions of doses, we now have an extraordinary amount of scientific evidence.”
“This review affirms that mRNA vaccines are a safe and highly effective platform, supported by rigorous testing and real-world monitoring. It provides an evidence-based foundation as this technology continues to expand into new areas of medicine,” Blakney said.
Rare Side Effects
Like any other medical treatment, mRNA vaccines can cause side effects. Most people experience only mild reactions such as pain at the injection site, tiredness or a slight fever that disappears within a few days.
The review found that serious side effects, including myocarditis, are rare. While myocarditis has been reported more often in younger males, researchers stressed that the risk remains very low. More importantly, the protection provided by the vaccines against severe illness, hospitalisation and death is far greater than the risk of these uncommon side effects. The review also highlighted strict manufacturing standards, quality controls and continuous safety monitoring that support public confidence.
Although the science behind mRNA was first discovered decades ago, the Covid-19 pandemic marked its first large-scale use. Its success has encouraged researchers to explore many new applications. Scientists are now developing mRNA vaccines for diseases such as influenza and respiratory syncytial virus (RSV). Researchers are also studying personalised cancer vaccines and RNA-based therapies that could be tailored to individual patients. Because mRNA vaccines can be designed and produced quickly, they offer a flexible and cost-effective way to respond to future disease outbreaks.
Experts also stress the importance of expanding vaccine production in low- and middle-income countries. Greater investment in local manufacturing, technology transfer and stronger regulatory systems could improve access, lower costs and ensure people around the world benefit from these advances.
Robin Shattock, of the UK’s Imperial College London and co-author of the study, said, “Expanding manufacturing capacity and ensuring equitable access in low- and middle-income countries is essential if mRNA vaccines are to fulfill their promise as a global public good.”
“By investing in technology transfer, local production, and robust regulatory systems, we can shorten supply chains, reduce costs, and ensure that people everywhere benefit from safe, effective vaccines beyond pandemics,” Shattock said.
