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.

The Motley Fool talked to Dr. Leo Nissola about what this hopeful development means for the world and for investors.

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Corinne Cardina: You mentioned Moderna already, but this is a company that's taking a pretty much the same approach of using the mRNA. Moderna's stock, it went up on the news. Investors clearly don't think this is a winner-take-all market. I would love to hear your thoughts on how you envision this plays out in terms of distribution. When do you think a vaccine might be available to the public? Are there certain groups of people who are going to get the vaccine first? Are we're going to have rolling different kinds of vaccines coming out? We'd love to hear your insights.

Dr. Leo Nissola: Yeah. I think there are many questions that remain. We don't know. You can still get asymptomatically infected while you have received Pfizer's vaccine. That's an important question. Meaning, is it clear that this vaccine is effective at preventing infection altogether? That might be a matter in the longer run, and we will see if it cuts down on transmission. But it's not required to protect at-risk individuals against severe disease outcomes. Though, Pfizer has enrolled adults and older adults in their trial. Right now, we don't know how the efficacy breaks out. It protects older individuals and younger people the same way. Knowing how the process works, we understand how vaccine trials work. These trials can determine if a vaccine protects against a coronavirus, but also if it protects against severe disease. That's a very important point to take into account. Moderna's vaccine is following the same biological rationale or scientific rationale of Pfizer's and its good news for them too.

Corinne Cardina has no position in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.