What Are the Different Ingredients Being Used in the COVID-19 mRNA Vaccines?

Dr. Paul Offit talks about what ingredients are — and are not — in COVID-19 mRNA vaccines.


What are the different ingredients being used in the covid-19 mRNA vaccines?

Paul Offit, MD: Hi, my name is Paul Offit from the Vaccine Education Center. One of the questions parents have about these two new vaccines, these so-called messenger RNA vaccines made by Pfizer and Moderna, these vaccines that are designed to prevent SARS-CoV-2 infections, is what's in it? I mean, how do I know that's safe, especially because it's sort of a new strategy to make a vaccine? Well, so here's what's in it.

One is so-called messenger RNA, which is a small genetic fragment that teaches our cells how to make proteins, in this case the SARS-CoV-2 spike protein, that protein that sits on the surface of the cell. Because when we make that protein, then we can make antibodies to that protein and prevent infection.

Now, messenger RNA is not certainly new to our cells. We all have thousands and thousands of copies of messenger RNA in all of our cells because our cells make proteins in order to stay alive. So that's not novel.

The second component is the so-called sort of lipid droplet, a little fatty droplet that incases that messenger RNA. Lipid also is not something that's new. Lipid is part of the membranes that surround cells. Lipids are part of the membranes that surround the nucleus. So again, lipids are not something that's novel. And we have lipid in our body all the time.

Another component is, are sort of salt, frankly, sodium chloride, just like the salt that is in table salt, and then sugars. The reason that those products are in vaccines is they sort of help buffer and stabilize this, so that these little nanoparticles can remain separate and so that they can be stable. All of that is in vaccines. So, nothing we haven't seen before; nothing we haven't experienced before.

But, I think probably more important than what is in vaccines is what isn’t in vaccines. What isn’t in vaccines are things like blood products, antibiotics, DNA, fetal cells, egg proteins, preservatives (like thimerosal, which is a mercury-containing preservative), or pork products; those are not part of vaccines. So, occasionally, people will look online and find misinformation regarding these mRNA vaccines that it may be including those materials that I just mentioned, but they don't.

So, I think the products that we're seeing in vaccines are products that we experience in nature all the time, which I think should be reassuring.

Thank you.

Related Centers and Programs: Vaccine Education Center

Last Reviewed on Feb 11, 2021