There is a small amount of data that suggests that just one dose of a coronavirus vaccine in a two-dose regimen can provide some protection against the coronavirus. Does this mean that people can safely receive one dose instead of two? It is too late for investors to start paying attention to companies working on a single dose vaccine, such as Johnson & Johnson (NYSE: JNJ)? Dr. Bruce Gellin of the Sabin Vaccine Institute joined Olivia Zitkus and Corinne Cardina of the Healthcare and Cannabis Bureau of Fool.com in an episode of December 18, Fool Live to discuss two-dose vaccines of Modern (NASDAQ: MRNA) and Pfizer (NYSE: PFE)–BioNTech (NASDAQ: BNTX) team.
Olivia Zitkus: Both vaccines are mRNA vaccines, messenger RNA vaccines. Although the two mRNA vaccines are intended to be a two-dose regimen, you vaccinate a person and then they return three or four weeks later, depending on the vaccine for your second dose, some people are wondering about the potential for just one dose of these mRNA vaccines. Notably, an opinion article in the New York Times published just today, I think this morning, questioned the possibility of vaccinating more people by administering just one of the two intended doses. I’m wondering what you think about this and what is the impact of this type of conversation on the public’s behavior?
Dr. Bruce Gellin: It is an important question. I think part of that is recognizing, I mean, there are 300 different approaches that are being done globally and you’re probably monitoring each one, but I think the interesting thing is that there’s a lot of interest, a lot of attention. Any scientist who has a vaccine approach has come forward and we will learn a lot from it. Not all 300 horses will finish the race, but I think we will learn a lot in the process. But with regard to this and two doses, some companies are focusing on a single dose. I think this is very important when you think about usability. From a program standpoint, finding a person for the first time to be vaccinated is difficult enough, getting them back when needed is actually a much more complicated challenge that we will have to deal with to try to make sure we provide protection. But the question that is really important, which was intriguing, and I think it’s probably the best you can say with the data, is that both mRNA vaccines are two-dose vaccines. The initial clinical trials of phase 1 and phase 2 trials are designed to determine what the right dose is, what the right dose range is, and show that the maximum immune response occurs after two doses. But as they were watching these studies intensely, you could follow people after the first dose, and you saw that around the two-week, 10-day, 14-day mark, there was a split in the curve. What this means is that in about 14 days, some people, even after the first dose, appear to be protected when compared to placebo. Interesting numbers, encouraging, but very small. Although we have seen this, what is called a point estimate, when you compare these numbers, it is in the range of 50%, which is intriguing, but as there are so small numbers, a confidence limit, as statisticians say, is quite broad, and if there was one or two differences between who is and is not in the placebo group, it will be quite different. The short story is until we know a lot more, two doses is what we need, and giving them the first dose can really cause a difficulty if people don’t get the full immunity they need. In doing so, we will be using many vaccines that may not protect the population as we think.
Zitkus: Okay, that length of immunity is still an issue with the two-dose vaccine. If we have people getting just one dose from a two-dose schedule, it really complicates the data picture.
Gellin: In fact, looking at the immunology of coronaviruses and other vaccines, we don’t expect lifelong protection, but we might be surprised. Given what we know about vaccinology and the immune response, a second dose is likely to give a better and longer response.