Diya Poluru '29

Vaccines prepare the immune system to fight harmful pathogens by exposing it to a safe version or piece of a disease-causing organism, enabling the body to recognize and resist future infection (Centers for Disease Control and Prevention, 2024). Traditional vaccines often use weakened or inactivated viruses to help the immune system defend your body without causing illness, and they have significantly reduced disease over decades (Li et al., 2025; CDC, 2024) Developing these vaccines can take many months or longer, which limits how quickly they can be used (Li et al., 2025). However, messenger RNA (mRNA) vaccines work by delivering instructions in the form of messenger ribonucleic acid, a type of molecule cells use to make proteins, so that cells can produce harmless viral proteins that trigger an immune response (MedlinePlus Genetics, 2022). This method has been used for vaccines against COVID-19 and is also being studied for other diseases and uses (MedlinePlus Genetics, 2022; Cleveland Clinic, 2025). 

The immune system responds to foreign proteins by producing antibodies, which are proteins that attach to pathogens and mark them for elimination by immune cells (CDC, 2024). In the case of mRNA vaccines, the vaccine contains instructions that correspond to a virus protein, causing cells to produce that protein and alert the immune system without exposing the body to the full, actual virus (MedlinePlus Genetics, 2022). Messenger RNA from the vaccine does not enter the nucleus of the cell and does not alter DNA, and it is naturally broken down after the protein is produced (MedlinePlus Genetics, 2022). These features ensure that individuals cannot become infected by the vaccine (MedlinePlus Genetics, 2022).

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Research on mRNA vaccines has been ongoing for a long time. Early experiments in the 1990s tested mRNA vaccines in mice, and clinical studies for diseases like rabies were progressing before the COVID-19 pandemic hit (Johns Hopkins Bloomberg School of Public Health, 2021). These earlier efforts laid a foundation for the rapid development of the first widely used mRNA vaccines during the global COVID-19 outbreak, which used mRNA instructions to generate the spike protein found on the surface of the SARS-CoV-2 virus, the virus that causes COVID-19 (Li et al., 2025; MedlinePlus Genetics, 2022). The rapid development was possible because mRNA can be synthesized in the laboratory without the need to grow whole viruses in cell cultures, which shortens production time and simplifies manufacturing (Cleveland Clinic, 2025; Penn Medicine, 2025). 

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Lipid nanoparticles, nanometer-wide spheres composed of fats, protect and carry mRNA into cells. These are used to deliver the vaccine instructions without decomposition (Li et al., 2025; Nature Reviews Drug Discovery, 2018). Once inside the cell’s cytoplasm, the mRNA is read by ribosomes, which are structures that assemble proteins based on genetic instructions. These instructions direct cells to produce a harmless viral protein that alerts the immune system (Li et al., 2025; MedlinePlus Genetics, 2022). The presence of the protein activates the immune system, and it then develops memory cells and antibodies ready to respond to future exposure to the real virus (CDC, 2024). 

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The first widely authorized mRNA vaccines, developed by Pfizer-BioNTech and Moderna, demonstrated strong immune responses and were approved for use against COVID-19, reducing the risk of severe illness and hospitalization (Li et al., 2025; Cleveland Clinic, 2025). Research teams are investigating mRNA vaccine designs for influenza, respiratory syncytial virus, and other infectious diseases, as well as vaccines to cause immune targeting of cancer cells (Li et al, 2025; Penn Medicine, 2025). Work at institutions like Penn Medicine includes experiment vaccines against the bird flu and efforts to develop vaccines for conditions such as HIV, hepatitis C, and tuberculosis (Penn Medicine, 2025). 

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Despite progress, challenges remain. Messenger RNA is unstable at normal temperatures and often requires storage at very low temperatures to maintain effectiveness (though, as of late, the vaccines are becoming more thermostable), which complicates distribution in some regions (Li et al., 2025). Scientists are studying ideas that might be stable at higher temperatures and are also working to help cells absorb mRNA more efficiently while preserving a strong immune response (Nature Reviews Drug Discovery, 2018). Researchers are still determining how long vaccine-induced protection lasts and how often doses need to be given (Li et al., 2025). 

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However, mRNA vaccines represent a breakthrough shift in how vaccine instructions can be delivered to cells, offering a method that can be produced quickly and adapted to new targets (Cleveland Clinic, 2025; Penn Medicine, 2025). As of late 2025, there have even been examples of personalized mRNA vaccines being actively developed and tested for cancer treatment, and they have actually shown significant success in improving the health of cancer patients, demonstrating that the potential for this field is massive (PubMed Central, 2025). Additionally, further laboratory and clinical research is needed to refine vaccine design and expand access across different populations, while we are making tremendous progress (Li et al., 2025). 

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In conclusion, mRNA vaccines represent a shift away from older vaccine methods by allowing immune protection to be built without using weakened or inactivated viruses. Improvement in stability and delivery could make this approach easier to deploy and adapt, expanding its use across a wider range of diseases and settings (Li et al., 2025; CDC, 2024).

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References 

Beyrer, C. (2021, October 6). The Long History of mRNA Vaccines | Johns Hopkins | Bloomberg School of Public Health. Johns Hopkins Bloomberg School of Public Health. Retrieved January 23, 2026, from https://publichealth.jhu.edu/2021/the-long-history-of-mrna-vaccines 

CDC. (2024, August 10). Explaining How Vaccines Work. CDC Vaccines and Immunizations. Retrieved January 20, 2026, from https://www.cdc.gov/vaccines/basics/explaining-how-vaccines-work.html Cleveland Clinic. (2024, October 25). mRNA Vaccines: What They Are & How They Work. Cleveland Clinic. Retrieved January 23, 2026, from 

https://my.clevelandclinic.org/health/treatments/21898-mrna-vaccines 

Li, J., Liu, Y., Dai, J., Yang, L., Xiong, F., Xia, J., Jin, J., Wu, Y., & Peng, X. (2025, October 30). mRNA Vaccines: Current Applications and Future Directions. PubMed Central. Retrieved January 23, 2026, from https://pmc.ncbi.nlm.nih.gov/articles/PMC12572956/ 

Magoola, M., & Niazi, S. K. (2025, June 4). Current Progress and Future Perspectives of RNA-Based Cancer Vaccines: A 2025 Update. PubMed Central. Retrieved January 23, 2026, from https://pmc.ncbi.nlm.nih.gov/articles/PMC12153701/ 

Mayo Clinic. (2025, October 21). Coronavirus disease 2019 (COVID-19) - Symptoms and causes. Mayo Clinic. Retrieved January 23, 2026, from 

https://www.mayoclinic.org/diseases-conditions/coronavirus/symptoms-causes/syc-20479963

MedlinePlus. (2022, November 21). What are mRNA vaccines and how do they work? MedlinePlus. Retrieved January 23, 2026, from 

https://medlineplus.gov/genetics/understanding/therapy/mrnavaccines/ 

Nature Reviews Drug Discovery. (2025, September 17). RNA modification systems as therapeutic targets. Nature Reviews Drug Discovery. Retrieved January 20, 2026, from 

https://www.nature.com/articles/s41573-025-01280-8 

Penn Medicine. (2025). World-changing mRNA vaccines. Penn Medicine. Retrieved January 21, 2026, from https://www.pennmedicine.org/about/pioneering-the-future-of-medicine/mrna