mRNA vaccines: How does it work?

Neil Dustin Benedict Agner ||

For several months, the world has been anxiously waiting for a sort of relief, a first-line prevention for the menace that plagued us ceaselessly – the COVID-19 pandemic. Finally, the long-awaited vaccine has arrived as Pfizer and Moderna announce their COVID-19 vaccine. These vaccines, just days apart, showed high levels of effectiveness against the disease. 

Pfizer announced the preliminary trial results of their Pfizer-BioNTech developed vaccine showing that it was 90% effective. Nine days later, it was followed up with final test results and two months of safety data, showing it was 95% effective. Similarly, Moderna announced that preliminary results for their own vaccine indicated that it was 94.5% effective. 

The two vaccines were developed using messenger RNA (mRNA). However, as this concept is relatively new, it has yet to be approved in vaccines until now. 

So how do mRNA vaccines work?

An mRNA vaccine works differently compared to live attenuated and inactivated vaccines. Instead of injecting the viral protein into the body, the person is injected a blueprint of the viral protein in the form of genetic material – the mRNA. When injected in the body, the cells use the genetic information (in the mRNA) to directly produce the viral protein in the body. 

Simply put, in traditional vaccines, the actual inactive virus, or the proteins it produces, are injected into the body. Conversely, the discovered vaccines inject the instructions for making the proteins the form of mRNA, so that the proteins are created inside the body by its own cells.

In the case of Pfizer’s and Moderna’s vaccines, the instructions in the mRNA injected are used by the cells to build the spike protein that the coronavirus uses to infect other cells. This spike protein is then recognized by the immune system and triggers it to produce antibodies and immune cells.

3D print of the spike protein of SARS-CoV-2, the virus that causes COVID-19. Spike proteins cover the surface of the virus and allow it to enter and infect human cells. Photo Credit: NIH

It will be another agonizing wait even as the vaccine signifies a turning point for the future.

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