How Does the COVID-19 mRNA Vaccine Work?

Biotechnological advances have allowed scientists to develop a vaccine against COVID-19 that pharmaceutical and biotechnology companies can manufacture relatively quickly and distribute around the globe, albeit with many supply chain challenges.  The combination of “warp speed” and “new technology” has made many people skeptical of the vaccine’s safety, a problem that could seriously hinder its rollout and our turn to relatively “normal” activities. Background on the “new” technology that has been under study for two decades and information on the clinical-trial requirements to ensure the safety of vaccines demonstrate that the initial mRNA vaccines are far safer than infection with SARS-CoV-2.  The utility of every new vaccine or treatment is a balance between benefit and risk, and in this case, most knowledgeable scientists and physicians would agree that the benefits far outweigh the risks.  

The vaccines currently authorized for emergency use by the FDA and EMA are both mRNA vaccines produced by BioNTech/Pfizer and Moderna. mRNA technology works by informing cells how to produce harmless proteins that match those on the SARS-CoV-2 virus (such as the “spike” protein found on the surface of the virus). After your cells produce this protein, the immune system responds by producing T-lymphocytes and B-lymphocytes that can identify the real virus in your body and kill it before it causes infection and spread of the disease to distant organs. Then, your body destroys the mRNA genetic material, leaving none of the nucleotides behind. 

While this may seem like a newly discovered technology, it has been studied extensively for its disease-fighting potential in mice back to the 1990s. However, scientists struggled to find a way to get the mRNA safely into the cells without the body destroying it on the way. Scientists continued work on the mRNA technology and discovered that a modified version of the mRNA was able to get into cells without destruction by an immune response. This research laid the groundwork for the subsequent development of mRNA vaccines for COVID-19, accelerating the process to get a vaccine into human studies at the beginning of 2020.

The COVID-19 public-health emergency allowed scientists to overlap trial phases, expediting the clinical-trial process. However, despite the accelerated timeline, the FDA set strict standards that all researchers were required to adhere to before the FDA authorized either vaccine for widespread use. Rigorous clinical trials established both the safety and efficacy (effectiveness) of the COVID-19 vaccine. Each vaccine candidate was studied in about 40,000 subjects in these trials.  In addition, the FDA will keep track of all reported adverse effects as the vaccine is administered to monitor for any problems or side effects that may arise following issuance of the EUA. Both manufacturers plan to obtain formal approval and licensure of their mRNA vaccine later this year after completing longer term follow up of patients enrolled in the original clinical trials.

The mRNA vaccines currently authorized for use by the FDA and EMA are both safe and effective for protection against development of COVID-19 disease. Both vaccines are approximately 95% effective, which means that getting a COVID-19 vaccine is one of the best steps you can take to protect against COVID-19, once the vaccine is available to you. However, ongoing clinical trials are still needed to ensure that the vaccines protect against the new variants or strains of the virus, prevent viral transmission, even if patients are asymptomatic, and to ensure that the vaccines can be administered safely with approximately the same level of efficacy in pregnant or lactating women, children of all ages, the elderly and those with a compromised immune system such as HIV-AIDS.

Sources: CDC, STAT, Johns Hopkins


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