Immunizations play an important role in saving millions of lives each year by preventing life-threatening diseases and illnesses.  The onset of the coronavirus pandemic in early 2020 prompted an urgent need for a vaccine that could be manufactured quickly and distributed in mass quantities.  The race to find a vaccine for SARS-CoV-2, the coronavirus that causes COVID-19, prompted new innovations in vaccine technology as scientists researched the possibility of messenger RNA (mRNA) vaccines against infectious diseases.

Vaccines train the immune system to recognize and respond to the proteins produced by disease-causing organisms, such as a virus or bacteria.  Conventional vaccines contain a weakened version of the live virus or a small amount of inactive virus that is injected into the body to provoke a response in the immune system.  mRNA vaccines work differently by replicating the genetic code of a virus to trick the body into producing antibodies without requiring the virus itself to be injected.

Ribonucleic acid (RNA) is a single-stranded molecule found in the nuclei of cells, and mRNA is a type of RNA that carries genetic code which produces the cell’s proteins.  An mRNA vaccine contains instructions that direct cells in the body to make antigens that will induce an immune response to prevent or fight disease.  Once antibodies are created, the body acquires a defense against infection.

There are several advantages of mRNA vaccines over conventional ones, including safety, efficacy and production.  mRNA vaccines are made with non-infectious material and are non-replicable, which means that the virus is not present in the vaccine and there is no potential risk of infection from the virus it mimics.  Early clinical trials of mRNA vaccines have produced a reliable immune response with minimal side effects; however, more large-scale human trials are needed to support these initial findings.  Unlike conventional vaccines, gene-based vaccines do not need to be grown in eggs or cells, a process that can be time-consuming and costly.  Instead, they are produced in a laboratory from a DNA template using readily available materials that allows for rapid mass-production. 

One challenge with mRNA vaccines is the requirement of ultra-cold temperatures for shipping and storage.  Researchers are working on ways to make mRNA vaccines more stable, particularly for countries that have limited refrigeration facilities.  Another disadvantage is the unknown length of protection that mRNA vaccines may provide against a disease – data that only can be acquired through more large-scale clinical trials. 

In addition to research on mRNA vaccines against COVID-19, the technology also is being used to create vaccines that can generate antibodies to target other infectious diseases, such as HIV, Zika, Ebola and influenza.  Cancer vaccines in which mRNA targets cancer-specific antigens also are being explored.  Clinical trials for mRNA vaccines are being conducted for a number of cancers, including esophageal, lung, ovarian, melanoma and blood cancers.

There is great potential for mRNA vaccines to become a standard treatment in medical care, but more research and clinical trials must be performed to determine their long-term effectiveness.  Two of the potential vaccines against COVID-19 being created are mRNA vaccines, which are among the first to be used in large-scale human trials.  If successful, the new vaccines could usher in a new approach to fighting infectious diseases.