Technology Tuesday: What is the COVID-19 mRNA Vaccine?
Coronavirus Disease 2019
The 2019 Coronavirus Disease (COVID-19) pandemic presented scientists with a challenge: they needed to quickly understand how the virus works in order to create ways to end the pandemic. From the start of the pandemic, scientists have been working to develop a vaccine to help the body prevent and fight an infection with SARS-COV-2 (the virus that leads to COVID-19).
What a coronavirus looks like. The molecule is round and red and has bumps on the outside surface called spike proteins that make it look like a crown.
Source: https://bpsbioscience.com/sars-cov-2-coronavirus-covid-19
SARS-COV-2 stands for “Severe acute respiratory syndrome” (SARS) “coronavirus” (COV) “2”. A virus is called a coronavirus when the proteins on the outside of the virus (spike proteins) look like a crown [1]. The first coronavirus that resulted in severe acute respiratory syndrome emerged in 2002 and was named SARS-COV because of the structure of the virus and its symptoms [4,8]. In 2019, a new coronavirus causing SARS-like symptoms emerged and was named SARS-COV-2. This 2019 variant of the SARS-coronavirus is what leads to the disease known as COVID-19. COVID-19 stands for “Coronavirus” (COVI) “disease” (D) “2019: (19). Severe acute respiratory syndrome (SARS) is just one known symptom of COVID-19 [4]. Other COVID-19 symptoms can be found on the Centers for Disease Control and Prevention (CDC) website at: https://www.cdc.gov/coronavirus/2019-ncov/symptoms-testing/symptoms.html.
How antibodies work to prevent COVID-19. If you are infected with the coronavirus, the spike proteins on the virus bind with your healthy cells and become infected. If you get an mRNA vaccine, your body creates antibodies (the red Y-shaped molecules in the image) that can bind to the spike proteins instead and stop the coronavirus from infecting your cells.
Spike proteins, which are what make the virus look like a crown, attach to sites called receptors on healthy cells in your body. This attachment allows the virus to infect the healthy cells [1]. When someone is infected with SARS-COV-2, the body makes proteins called antibodies that stop the spike protein on the virus from attaching to receptors on healthy cells [5]. This helps to stop the virus from continuing to infect the body [8]. In other words, the antibodies “block” the virus known as SARS-COV-2 and helps the body to fight sickness symptoms known as COVID-19. Antibodies can also stay in your body for a while and are important for preventing future infections from the virus.
About mRNA Vaccines
mRNA vaccines have been used and studied in clinical trials for other viruses such as Zika, Ebola, influenza (the flu), rabies, and cytomegalovirus [6,8,9]. Also, mRNA has been and is currently used in cancer research to try to teach the body to recognize and respond to proteins produced by tumors [2,6]. mRNA can activate two types of immune cells called T-cells, which kill infected cells, and B-cells, which make antibodies [2,9].
Traditional vaccines that have been produced in the past contain either a weak, dead, or noninfectious version of the virus it is trying to protect you against. These vaccines contain a version of the virus that can teach your body how to fight the virus without actually becoming infected with the virus. On the other hand, mRNA vaccines do not contain any type of a virus. Instead, they teach your body how to identify a structure on a virus and fight that [3,7]. Since large amounts of the virus do not have to be handled or altered in order to create the vaccine, mRNA vaccines can be developed and proved safe within a shorter period of time compared to virus-containing vaccines [3,9].
In the future, other vaccines for COVID-19 may be developed. But in 2020, one of the safest, quickest, and most effective ways to respond to the COVID-19 pandemic was to use previous research to create the mRNA vaccine.
The COVID-19 mRNA Vaccine
Scientists have known about the relationship between antibodies and spike proteins since the first SARS-COV outbreak in 2002 [9]. So, when researchers were developing a vaccine for COVID-19 they used that previous information to create a vaccine that teaches the body how to create antibodies that can fight off an infection with SARS-COV-2. The vaccine created in 2020 by Moderna and Pfizer used mRNA to teach the body how to fight the virus [7].
Flow chart of how proteins are made. DNA is a double-stranded molecule that stores instructions for making proteins. mRNA is single-stranded and made from DNA and carries a temporary set of instructions for cells to make proteins. Proteins are made from mRNA and are the building blocks of life because they perform the functions required by every cell.
Source: https://www.sec.gov/Archives/edgar/data/1682852/000168285220000006/moderna10-k12312019.htm
mRNA stands for “messenger” (m) ribonucleic acid (RNA). Normally in your body, DNA carries instructions that are copied into mRNA, which is used to tell your cells how to create specific types of proteins [3,7]. The copy of instructions (mRNA) is only used by the cells to create the specified proteins and is destroyed during the process.
The COVID-19 vaccine contains already-made mRNA that carries instructions to make a harmless copy of spike proteins (the proteins that can also be found on the outside of the coronavirus). After the vaccine is given in the upper arm muscle, mRNA enters healthy cells in your body and teaches them how to make a harmless version of spike proteins that are located on their own surfaces [6].
Once the spike proteins are made, your body realizes that those proteins shouldn’t be there and your immune system creates antibodies to fight against the foreign proteins. This immune response teaches your body how to fight against a future infection. In this case, your body learns that if it becomes exposed to SARS-COV-2, it should create antibodies to stop spike proteins on the virus from attaching to receptors on your healthy cells and infecting your body [6]. Stopping this infection will prevent you from developing COVID-19, which is the disease that you get when you are infected with SARS-COV-2.
The COVID-19 mRNA vaccine does not contain any amount of a virus, which means that there is no chance that you will get COVID-19 from the vaccine [7]. However, it may still cause feelings of sickness because your body is creating a “practice” immune response to the spike harmless proteins that are created by the mRNA.
Other Resources
Here are some links to other resources that may help you better understand mRNA vaccines for COVID-19!
References:
Amanat, F., & Krammer, F. (2020). SARS-CoV-2 vaccines: status report. Immunity, 52(4), 583-589.
Pardi, N., Hogan, M. J., & Weissman, D. (2020). Recent advances in mRNA vaccine technology. Current opinion in immunology, 65, 14-20.
Schlake, T., Thess, A., Fotin-Mleczek, M., & Kallen, K. J. (2012). Developing mRNA-vaccine technologies. RNA biology, 9(11), 1319-1330.
Seladi-Schulman, J. (2020, April 20) COVID-19 vs. SARS: How do they differ? Healthline. Retrieved Feb. 16, 2021. https://www.healthline.com/health/coronavirus-vs-sars#symptoms
Test for past infection. (2021, Feb. 2). Centers for Disease Control and Prevention. Retrieved Feb. 16, 2021. https://www.cdc.gov/coronavirus/2019-ncov/testing/serology-overview.html
Understanding mRNA COVID-19 vaccines. (2021, March 4). Centers for Disease Control and Prevention. Retrieved April 9, 2021. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/mrna.html
What is messenger RNA? (2020, Dec. 21). UPMC HealthBeat. Retrieved April 9, 2021. https://share.upmc.com/2020/11/what-is-messenger-rna/?vwo=homepage-hero_redesign
Whittaker, G. R., & Daniel, S. (2020). Going back in time for an antibody to fight COVID-19. Nature. Retrieved April 9, 2021. https://www.nature.com/articles/d41586-020-01816-5
Zhang, N. N., Li, X. F., Deng, Y. Q., Zhao, H., Huang, Y. J., Yang, G., ... & Qin, C. F. (2020). A thermostable mRNA vaccine against COVID-19. Cell, 182(5), 1271-1283.