Pfizer (NYSE:PFE) and its German partner BioNTech (NASDAQ:BNTX) reported incredible efficacy data from a phase 3 trial for their mRNA coronavirus vaccine candidate. This news, paired with the equally impressive data from Moderna (NASDAQ:MRNA) about its candidate that takes a similar approach, inspired much hope around the world and injected optimism into the stock market.

We talked to Dr. Angela Rasmussen, a virologist and Associate Research Scientist at Columbia Center for Infection and Immunity, about what investors should know about how mRNA vaccines work and why they would be revolutionary if launched on the market.



Corinne Cardina: I would love to talk about the mechanism of this vaccine. An mRNA vaccine has never been approved and marketed before. Can you talk to us a little bit about how this kind of vaccine differs from a more traditional vaccine like the flu shot that we're all used to getting every year?

Dr. Angela Rasmussen: Right. Yeah, absolutely. The flu shot is what is called an inactivated vaccine. Basically, it's pretty simple. You take a bunch of chicken eggs that have been fertilized, you inject them with your virus stock. You use those chicken eggs to grow up a bunch of virus because flu grows exceptionally well in chicken eggs. Then you inactivate that virus. You render it non-infectious usually by some chemical treatment. Then you give that vaccine to people. Your immune system will respond to what are called the antigen, they're proteins on the outside of the virus particle. That's how you develop immunity with that type of vaccine. An mRNA vaccine takes the mRNA or messenger RNA which is the instructions basically to yourselves, protein-making machinery to make the antigen. Rather than giving you an inactivated virus particle from SARS-coronavirus-2, they give you an mRNA that expresses the spike protein on the surface of SARS-coronavirus-2. So your immune system will still recognize that protein as being foreign and will respond to it. It circumvents the need to actually grow up a lot of virus. It makes yourselves basically do the work of expressing that antigen for your immune system to recognize for you. Both the Pfizer vaccine and the Moderna vaccine are mRNA vaccines that work this way. You're correct. They have never been approved for human use. They have had some clinical trials in Phase 1 for other viral infections. There is some precedent for testing them in people. But they have never been used on a wide scale, certainly not in circumstances like this.

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