Pfizer–BioNTech and Moderna mRNA Vaccines
Vaccines usually function by injecting a safe version of a virus into a patient’s body. Sometimes it’s a whole virus, parts of a virus, or a different virus that can still teach our immune system about the intended target virus. The vaccine essentially gives our immune cells a dummy to fight so they are prepared for the real thing.
mRNA vaccines are different. Cells in your body contain DNA, a code for creating the proteins we’re made of. They function as a set of instructions for building our bodies. mRNA, or messenger RNA, plays a critical role in the process of interpreting your body’s instructions for making proteins.
So, instead of injecting a virus, some COVID-19 vaccines inject pieces of mRNA. Using the dummy analogy, the injected mRNA are instructions for our cells to create their own dummies to learn from.
Those dummies take the form of specific proteins like the ones found on the surface of infectious agents. Our cells build the dummy proteins, recognize that the proteins should not be in our bodies, then send our immune system to fight the dummy proteins. This builds our immunity, but the process takes time.
The two COVID-19 vaccines currently approved for emergency use here in the United States are both mRNA vaccines. The dummy that the mRNA in the vaccine helps our body make is a harmless piece of a protein found in the spikes of the virus that cause COVID-19. The spikes are what give the virus access to our cells, so they are an effective and easy target.
This mRNA process has been the target of widespread misinformation. Though you may hear otherwise on social media, the mRNA does not alter your DNA, it only uses the process of creating proteins to construct the dummies for our bodies to fight. The mRNA is destroyed in the process.
These vaccines use a harmless virus to deliver DNA to your cells. Once injected, it then works in a similar way to the mRNA vaccines. The DNA delivered by the harmless virus acts as instructions for your cells to create dummy proteins for your immune system to fight.
The harmless virus does not replicate itself. The DNA that it injects into your cells does not replicate or become a permanent part of you. Rather, it is destroyed when the immune system fights the dummy protein.
Though many of the mechanisms are like the mRNA vaccine, vector vaccines are easier to transport. The DNA is not as fragile as the mRNA.
No vector vaccines are approved in the United States as of publication, but there likely will be approved vector vaccines in the near future.
The Oxford–AstraZeneca vaccine is a vector vaccine that may see approval in the United States. Russia’s Sputnik V vaccine, China’s Convidicea vaccine, and Ad26.COV2.S, also known as the Johnson and Johnson vaccine, are all vector vaccines.
Inactivated Virus COVID-19 Vaccines
These three vaccines are not approved in the United States as of publication but are approved in other parts of the world. They function like conventional vaccines with a safe version of the virus injected and used as a dummy by the body’s immune system.
BBIBP-CorV was developed and approved in China. It has less storage and transportation requirements, making it easier to distribute. The developers claim it has a slightly lower effectiveness than the mRNA vaccines, but there is a lack of publicly available data and some conflicting numbers surrounding its use.
CoronaVac was developed in China as well. Though approved in some countries, it has a much lower effectiveness than either the BBIBP-CorV vaccine or the mRNA vaccines.
BBV152 was developed in India and is approved for monitored emergency use within the country. The effectiveness of the vaccine is not yet known.