's Healthcare and Cannabis Bureau Chief Corinne Cardina interviewed Richard Horton on Motley Fool Live on Oct. 9. Horton runs the British medical journal The Lancet and has been at the forefront of publishing data about the coronavirus pandemic this year. He also recently published a book called The COVID-19 Catastrophe.

Here, Horton explains how investors should evaluate the data about coronavirus candidates in late-stage trials including those being developed by Pfizer (NYSE:PFE) and BioNTech (NASDAQ:BNTX), as well as by Moderna (NASDAQ:MRNA).


Horton: There are about nine or 10 vaccines, different categories of vaccine in these late-stage trials. These trials are going on in countries around the world where the virus is still raging. What we have been looking for are two parts to this. First of all, as you say, efficacy. Does the vaccine work? So far the evidence we've got is we've got nine or so vaccines that definitely stimulate a strong immune response. That's excellent. But now we have to see that it actually protects against infection, or if you get the disease, it reduces the risk of a severe outcome or even death from the disease. Now, the question is, how much protection can the vaccine give you? It's not going to be 100% effective, Corinne. No vaccine is 100% effective. What's the minimum that we would need? Most people will say that if we have a vaccine that's 50% effective, that's good enough. That's what I'm looking for. I'm looking for a vaccine that has a minimum effectiveness of about 50%. If we have that, that will make a big impact. On safety, now that's a tougher question because safety is something that you often only see. You can only assess that accurately in the long-term. So what I'm unlikely going to be able to say is that, so far, based on the trial in a limited period, the vaccine is safe, and then we will have it licensed. The regulator will pass it, but then we're going to have to keep a very close eye on the long-term follow-up of people who have taken the vaccine to make sure that nothing unusual, surprising jumps out. So 50% efficacy and keep a close eye on safety. That's why I'm worried about president Trump's comment that we'll have a vaccine by the end of October because based on my knowledge of where we are with the vaccine trials, it's just cannot be possible that we will have a vaccine that will be available for public use by the end of October. I just don't see that.

Cardina: Yeah. It's important not to erode the public's trust in the vaccine because we need people to take the vaccine in order for the outcome to be what it is intended to be.

Horton: Well, you're right. Actually, I have a few worries about that because in China and in Russia, their vaccines, they are actually being rolled out to give to people, not members of the public, but members of the military. My concern is, and this is on the basis of having not done these big trials, so they're gambling and that gamble that they're taking may pay off. But if it doesn't pay off and there is a problem with one of those vaccines, that will have a global impact because I think in the public's mind, that could easily lead to a distrust, even a destruction in the credibility of the science, and that would be a terrifying disaster.

Cardina: Absolutely. We've gotten a question that I think is really relevant to this conversation from one of our viewers. Someone asked, what do you think the biggest misconception is about a COVID vaccine?

Horton: The biggest misconception I think is that it's going to be a magic bullet. If we have a vaccine, it will turn the pandemic off just like that and we can all go back to our normal lives. The sad truth is that that is not the case. Let me take you back to 2002, 2003 when there was another SARS virus that came out of the woodwork in China again and got distributed to half a dozen countries around the world. By the middle of 2003, it disappeared and we've never seen it again. It vanished. This virus is not that virus. This virus is now in every population, every community around the world, and we have to live with it. A vaccine will be an important tool in building up population immunity, but the virus is still going to be among us. The idea that we can erase, or eliminate, or eradicate the virus from society just is not true. I think that's one of the more dangerous myths. We have to come to terms. The way I would put it is a kind of peaceful coexistence with the virus. We have to live side-by-side with the virus. We have to renegotiate our relationship with the virus. If we understand that we have to do that, I think we will be much better placed to be planning our futures.

Cardina: A quote that, I don't remember who said it, maybe you do, but in the book, it says that if you've seen one pandemic, you've seen one pandemic. That really stuck with me. Who said that?

Horton: It's a guy called Adam Kucharski. He's a mathematical modeler at the London School of Hygiene and Tropical Medicine and he studied lots of epidemics, and they're all different. You can draw some lessons, general lessons, but by and large, when you get down to the detail, everyone is different.

Cardina: Yeah, absolutely. Talking about all the different vaccine candidates that we'll have data coming up soon, I'm curious about and I think our readers are curious, too, or viewers. We've gotten a couple of questions. When you look at the vaccines that are in phase 3, are there any that are taking a particular approach that you think is most compelling, whether it's mRNA, DNA, weakened virus? Any thoughts on that?

Horton: That's a hotly debated subject. Some of the, shall we say, fancier vaccines, that's the mRNA vaccines, I mean, they are technologically the most advanced, but some people believe that may be the good old-fashioned approach might be less exciting, technically, the science may not be as advanced, but actually they might work more effectively. That's the inactivated viral vaccines. That's a big, big debate. Is it the smart science that's going to win or is it the tried and tested rather old-fashioned, decades old approach? Another debate is over what's called the adenoviral vectors. One way of getting immunity is you basically stick parts of the coronavirus onto another virus, what's called an adenovirus, and if you give those two adjunct together, then the adenovirus is very effective at getting the coronavirus into the human body. Now the debate is, what sort of adenovirus should you have? The Oxford Group have used a chimpanzee adenovirus, the Russian group have used a human adenovirus, and the Russian team has been very vocal about saying that the human adenovirus is going to be a much more effective vector means of getting the coronavirus antigen into the human body. We don't know. These are speculations at the moment, and it's going to take us until the end of the year to find out the answer.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.