UF Health researcher answers questions about the latest COVID-19 vaccine

George Trotman, 68, receives a COVID-19 vaccination from a UF Health vaccinator at the Mt. Moriah Missionary Baptist Church in Gainesville recently. (Photo by Jesse S. Jones)

Courtesy of UF Health


And soon, there will be three.

Johnson & Johnson recently submitted its COVID-19 vaccine to the U.S. Food and Drug Administration (FDA) for emergency use authorization. That step could eventually make it the third vaccine to be approved in the battle against the novel coronavirus pandemic, joining vaccines made by Moderna and Pfizer with its German partner BioNTech.

It might be March before the Johnson & Johnson’s entry into the race to vaccinate the nation and world wins FDA approval.

Cindy A. Prins, Ph.D., M.P.H., a University of Florida Health infectious disease epidemiologist who is an associate professor in the UF College of Public Health and Health Professions and the UF College of Medicine, explains key points about this newest player on the COVID-19 vaccination front.

Question: Why is it important to have yet another vaccine available?

Answer: Relying simply on one vaccine means that you’ve only got one manufacturer providing a lot of doses, not only in our country but around the world. It’s really helpful to have multiple manufacturers, multiple vaccines, and also multiple types of vaccines to have the capacity to produce enough vaccine to get everyone immunized as quickly as possible.

Q: Which vaccine should people get?

A: The best vaccine is the one that you can get in your arm now. I wouldn’t hold out for one vaccine versus another. I know that some people are looking to do that. But what’s critical right now is to get immunized. In the time that people may wait thinking they might have a preference, they could potentially get infected with COVID-19. These are all really good vaccines, and there’s value in getting any one of them.

Q: How effective is the Johnson & Johnson vaccine?

A: Johnson & Johnson conducted its vaccine trials in several different countries, reporting efficacy within the United States, Latin America, and South Africa. When you look at all three areas overall, the vaccine was 85% efficacious in preventing severe COVID-19, with no reports of hospitalization or death 28 days after vaccination. It was 72% efficacious in preventing moderate to severe cases of COVID-19 in the U.S. That’s actually very good. It was 66% overall in preventing moderate to severe cases if you look at all of those areas together. But that number dropped to 57% in South Africa, where we’ve seen reports of this new coronavirus variant.

Q: Does the Johnson & Johnson vaccine have advantages over Moderna’s or Pfizer’s?

A: Yes. The primary benefit is that it’s a single-dose vaccine, while the Moderna and Pfizer vaccines require two shots several weeks apart. Any time you need to bring someone back for a second dose, that can create complications of getting folks scheduled, getting them there. It is nice to have a single-dose vaccine. One and done.

Another thing that’s nice about the Johnson & Johnson vaccine is that it’s actually a more stable vaccine since it uses DNA instead of mRNA. And so it can be stored in a refrigerator for up to three months. There’s not quite that panic of having to get every single dose out of that vial within six hours like there is with the mRNA vaccines.

Q: How does the Johnson & Johnson vaccine work?

A: This vaccine uses an inactive version of a common cold virus called adenovirus. This virus is something that all of us encounter as a seasonal cold. This adenovirus vector, it’s really just a package to deliver a harmless double-stranded piece of the coronavirus’ DNA code to your cells so your body can make some copies of the virus’ spike protein. The adenovirus is already able to get into your cells like a key unlocking the door, allowing that incomplete piece of coronavirus DNA to then get inside to the cell’s nucleus. That DNA doesn’t become part of your genome. The cell, using that piece of coronavirus DNA, makes the messenger RNA, or mRNA, copy that codes for the coronavirus spike proteins. Then, when the cell makes these spike proteins, your immune system will recognize them as foreign and react to destroy them, and it creates antibodies that can protect you, should you become infected with the coronavirus later. The cells will break down and get rid of the COVID-19 DNA, mRNA, and proteins, but your immune response will keep going.

Q: Don’t the Moderna and Pfizer vaccines use mRNA, too?

A: They do. They start with the mRNA in a lipid bubble that is injected when you’re vaccinated. The mRNA in the Moderna and Pfizer vaccine doesn’t go into the cell nucleus because it doesn’t have to, once it’s already in a form to code for the spike protein. All three vaccines produce the spike protein, and the body’s immune reaction is the same for all. It’s the delivery method that’s different.

Q: Does the Johnson & Johnson vaccine actually inject you with either live adenovirus or coronavirus?

A: Absolutely not. These are small pieces of the viruses, not the viruses themselves. You cannot get the coronavirus through a vaccination, and you can’t be infected with the adenovirus, either. If you get side effects, it’s because your immune system is doing its job by reacting to something foreign, which in this case is just the spike protein.

Q: Are the side effects to the Johnson & Johnson vaccine similar to what you might experience for any vaccine, including Moderna’s and Pfizer’s?

A: Yes. Johnson & Johnson saw some minor fever. They saw headaches and body aches and fatigue, which were not major. And with this vaccine it’s only one dose. So, you don’t have the possibility of dealing with side effects for two different doses.