The Atlantic published an informative article discussing the mRNA vaccines developed by BioNTech/Pfizer and Moderna and what makes them special, as well as the general vaccine efforts.
It is no coincidence that the mRNA vaccines are ahead in the game since one of their key advantages is flexibility and speed of development. This would be the first application of this technology so if it pushes through it could lead to a paradigm change in vaccine development for other viruses or even cancer. I have talked to several scientists who are even more excited about the potential of this paradigm change than its application to SARS-CoV-2, and I feel that way myself.
Viruses like SARS-CoV-2 work by gaining entry into the cytoplasm of a cell using the spike protein and highjacking the cell’s processes to replicate itself. These mRNA viruses contain a small part of the mRNA of the virus coding for the spike protein, which allows it to gain entry into the cell and cause production of the spike protein, inducing an immune response to it, but is not dangerous in the sense that it does not contain the rest of the virus. Since the essential part of SARS-CoV-2 is the spike protein, this effectively trains the immune system to recognize and neutralize the virus should it encounter it at a later date.
Most other SARS-CoV-2 vaccines also target the spike protein, but many use other more traditional technologies that embed the spike protein material in a weakened or inactivated virus or some other viral material. These technologies do not allow entry into the cells, so that while they produce antibodies, they do not produce the T-cells that comprise an important component of immune response. Thus, the mRNA-based vaccines have potential to provide a more complete and durable immune response.
More studies need to be done on these vaccines to establish their short and long term safety, and characterize the robustness and durability of the immunity they provide, but the efficacy results from these two mRNA vaccines that have come in stronger than expected generates a lot of excitement and hope that they can play a key role in ending the pandemic.
Figure from nature.com