mRNA vaccines – What they are and what they are not 

CEPI’s mission to accelerate vaccine development against infectious diseases is underpinned by an approach that explores the potential for a range of different vaccine technologies, all or any of which might be tailored to respond quickly and effectively to a future epidemic or pandemic threat. 

By investing in research and development for multiple types of vaccine platform, such as viral vector, protein subunit and mRNA technologies, CEPI mitigates against the risk of relying on a single technology. This increases the likelihood of successfully developing safe and effective vaccines for both known epidemic threats and future novel ‘Disease X’ threats. 

mRNA vaccines have helped to save millions of lives, playing a vital role in global response to COVID-19. Scientists are now looking at ways to use these scientific advances to combat the next viral pandemic threat, potentially within 100 days of identification, and build on existing efforts to tailor mRNA vaccines so that that may even cure cancer. 

Using ‘Answer the Public’, we analysed some of the most popular search terms related to mRNA vaccines  across China, Switzerland and the United States, which were among the top countries searching ‘mRNA’ over the past 12 months, according to Google Trends at the time of publishing. 

Those questions and CEPI’s answers are below… 

What is mRNA? 

mRNA stands for messenger ribonucleic acid. Discovered in the early 1960s, it is a miniscule but vital messenger inside cells that carries essential instructions from the DNA in chromosomes to the part of the cell that builds proteins. 

Proteins are essential for life, they are the building blocks of cells, tissues and organs and play a vital role in bodily functions such as defending against infections. 

How do mRNA vaccines work? 

mRNA vaccines use synthetic mRNA—mRNA that is safely engineered in a laboratory to mimic natural biological processes.  

The vaccines use this mRNA to teach cells how to make a protein, or a small part of a protein, from a specific pathogen that triggers an immune response.  

This immune response, which produces antibodies, is what helps protect a vaccinated person from getting sick from that pathogen in the future.  

mRNA vaccines do not alter DNA. The mRNA in them cannot combine with or interact with DNA. mRNA does not stay in the body for very long. After it has done its job of teaching cells to make the protein, the cells break it down and it leaves the body as waste. 

Are mRNA vaccines safe?  

Yes. The first fully developed, tested and approved mRNA vaccines were the COVID-19 vaccines made by the pharmaceutical companies Pfizer/BioNtech and Moderna.  

But the idea of mRNA vaccines was far from new. Scientists had been working for decades conducting research into how to best make mRNA vaccines and ensure they delivered the correct protein-making instructions in the correct way to be safe and effective. As part of that research, scientists were exploring potential mRNA vaccines against diseases such as flu, Zika and Rabies. 

Before they were rolled out, the mRNA vaccines approved for use against COVID-19 were extensively tested in tens of thousands of people for safety and efficacy in rigorous clinical trials and approved by expert regulators around the world. Since then, hundreds of millions of people worldwide have received doses of the vaccines, which continue to be safe and protect against severe disease. 

Can mRNA vaccines have side effects? 

All vaccines and medicines can have side effects, but serious side effects are extremely rare and far outweighed by the risks of the diseases they are designed to protect against.  

In rare instances, mRNA COVID-19 vaccines have been linked to inflammation of the heart muscle (myocarditis) and the fluid-filled sack that holds the heart (pericarditis). These symptoms are also known complications of COVID-19 infection.  

There is no evidence that mRNA vaccines affect fertility nor that they increase the risk of blood clots or any type of cancer.  

What are the advantages of mRNA vaccines? 

In short—speed and scale. mRNA vaccine technology allows vaccines to be designed and produced more quickly than traditional vaccines. This makes them a good rapid-response option when scientists need to make new vaccines against a pathogen that is infecting people in a fast-spreading outbreak or epidemic 

mRNA vaccines are also more adaptable than other types of vaccines, meaning they can be updated or revised quickly to protect against new viral variants.  

However, safety and efficacy testing of new vaccines follows a regulated path that is no different for mRNA vaccines than for any other new vaccine. 

mRNA technology is also being used by scientists working on ways of targeting cancer and certain rare diseases where mRNA-based therapeutics can be specifically targeted or even “personalised”.