Johnson & Johnson’s new COVID vaccine: How it compares to Pfizer and Moderna

Written by Amy Ta, produced by Bennett Purser

Johnson & Johnson released the results of its clinical trials late last week and submitted them to the FDA for approval. Unlike the vaccines from Pfizer-BioNtech and Moderna, this one is a single shot, it doesn’t have to be stored at freezing temperatures (it only has to be in a regular fridge), and it’s less expensive (about $10 per dose). 

However, Pfizer and Moderna’s vaccines are more effective, with about a 95% efficacy rate. Dr. Anthony Fauci told the New York Press Club on Friday, “The results were interesting because it was conducted in the United States as well as South Africa and Brazil. … The efficacy rate in the U.S. was 72%. Now at first glance, that might not seem as good at 94 or 95%, but the important part of the whole thing was that for advanced, severe disease, it was quite effective. Overall it was about 85% effective, and there were no hospitalizations or deaths in the individuals who were vaccinated.”

Dr. Edward Jones-Lopez, assistant professor of Medicine at USC’s Keck School of Medicine, says it’s unusual to have a 95% efficacy rate. 

“Among the 30 or 40 vaccines out there that are in clinical use, there's maybe just a couple of others that have hit 90% efficacy or above. It's very, very unusual for that level of efficacy. And it's probably related to the mRNA platform itself. That is a very promising platform that is brand new. So it's going to be very difficult, frankly, for other vaccines using older technologies,” he says. 

Jones-Lopez says it’s not only about the efficacy estimate, but side effects. 

He points out that Johnson & Johnson made a general announcement and didn’t go into details that scientists and doctors look for. “Overall, there are really no concerning safety signals as of now,” he says. 

Jones-Lopez believes that within the next three months, Johnson & Johnson’s vaccine (along with those from AstraZeneca and Novavax) will gain FDA approval. He notes that the approval process in other countries is separate from the U.S. For example, AstraZeneca’s vaccine is already approved in the UK and India. 

Extra shots to defend against new COVID strains? 

When it comes to mutations, it appears that Johnson & Johnson’s vaccine is not as effective against the South African strain. 

Johnson & Johnson and Novavax have said that their efficacy against the new variants drops 10 to 30% (based on the current available data), according to Jones-Lopez. 

If people already received Pfizer or Madonna vaccines, would they have to get a third shot? Jones-Lopez says that is a likely scenario, and that mutations occur only if the virus is actively circulating. 

“What we're seeing right now is the virus drifting away from the original variant. But there is at least a theoretical concern that that change could be much more significant. And that's actually what is behind these influenza pandemic springs, where the change, instead of being a small change compared to its ancestors, it's a major change. And that creates … a brand new strain that, in essence, nullifies all of our previous efforts. There's right now no evidence that this could happen.”

He says overall, there's a lot of concern that variants may minimize the impact of vaccines, and companies will have to generate new vaccines to complement the defense provided by initial vaccines. 



  • Dr. Edward Jones Lopez - MD, MS, assistant professor of medicine at the Keck School of Medicine at University of Southern California; investigator of the AstraZeneca vaccine trial in the U.S.