COVID-19 vaccination has now begun. The first Americans began to receive Pfizer's (NYSE:PFE) coronavirus vaccine earlier this week. Moderna's (NASDAQ:MRNA) coronavirus vaccine could soon win emergency use authorization (EUA) as well. In this Motley Fool Live video recorded on Dec. 11, 2020, Healthcare and Cannabis Bureau Chief Corinne Cardina talked with immunotherapy scientist Dr. Leo Nissola about how these vaccines could help achieve herd immunity.

Corrine Cardina: You mentioned herd immunity. I think there's a little bit of confusion about what that means. There's the herd immunity that can happen when you just let a virus rampage throughout a population and that's one thing, but there is another version of herd immunity where we're talking about getting people immunity through vaccination.

Can you speak a little bit about what herd immunity is, why it's important, and how it factors into us starting to vaccinate our population in the US?

Dr. Leo Nissola: Of course. Basically, we have now a virus that we're not immune to. We have a virus that we have never encountered before. So we need people to not get sick from this virus and that's what we're looking for when you talk about immunity against this virus.

There are multiple ways that the human bodies are able to reach that immunity level that we're talking about for a year. One of them is developing a vaccine that will trigger immune responses just enough to create antibodies that will protect you from getting sick and from getting severe features of the disease. There's also the possibility of getting sick and developing natural antibodies.

One of the challenges of getting sick and developing antibodies with a novel virus that we have never encountered before is that we don't know how long those natural antibodies would actually last in your body. Some viruses are able to develop and trigger immune response that will last for years, and some others have not the same capability.

When we talk about herd immunity, what we're basically talking about is the possibility of a large group of people to develop antibodies against this specific virus. Whether that is achieved via natural pathways, where you're just letting the virus go around on the community and cause the damage that it's causing or you develop herd immunity by immunization, by actively triggering immune responses via a vaccine.

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