J and J Vaccine

How is the Johnson & Johnson vaccine different?

Johnson & Johnson is the third drugmaker to get emergency use authorization from the Food & Drug Administration for its COVID-19 vaccine. Much like the Pfizer and Moderna vaccines, Johnson & Johnson’s works by teaching the body how to build the spike protein found on the surface of the SARS-CoV-2 virus — thereby triggering an immune response against it. But unlike its predecessors, this one uses an inactivated virus instead of messenger RNA to carry the genetic code. J&J’s single dose proved 72 percent effective at preventing COVID-19 in clinical trials in the U.S., but additional research has shown that the number is likely even higher when it comes to preventing severe disease: 85 percent.

Is the Johnson & Johnson vaccine inferior to the others?

Local news reports show that many people have begun asking to be prioritized for Moderna or Pfizer due to the higher efficacy rates of those vaccines. But Dr. Aditya Shah, an infectious disease specialist at the Mayo Clinic, explains that the numbers may not tell the real story. “Vaccine efficacy percentages only matter when the majority of the population gets vaccinated, that is how it works,” Shah says. “Those individual numbers are based on studies done in 40,000, 50,000, 60,000 people — the number is a constant moving target based on how many people get vaccinated.”

New York Times journalist Carl Zimmer also pointed out this week on the podcast The Daily that the timeline of the vaccine trials matters. “Pfizer and Moderna started their trial in late July; Johnson & Johnson didn’t start for a couple of months after that. So by the time that Johnson & Johnson had a lot of recruits getting vaccinated, we were in the middle of a really intense surge of COVID, much bigger than what we had dealt with before,” Zimmer said. “And what vaccine developers have found is that if you run a trial when rates are really high, you might end up with an efficacy estimate that ends up being low. And that’s just because your volunteers are getting exposed to the virus more.”