When it comes to vaccine efficacy, here’s why 94% isn’t much different than 72%

Dr. Richard Marlink. (File photo)

When the news that Johnson & Johnson had completed Phase 3 of its clinical trial and that its one-shot vaccine would soon be available finally was released Friday morning, there was unbridled excitement.

It would be a game-changer, many said.

Then, the efficacy numbers came out. And the average Joes — the people who don’t fully understand trial data — let out a collective groan. After all, who wants a vaccine with a success rate of 72% versus the Pfizer and Moderna vaccines, which have a rate of 94-95%.

Never mind that the J&J vaccine is showing 85% efficacy against severe disease and 100% protection against hospitalization and death. The general public just heard 72% compared with 94%. And everybody knows an “A” student is much better than a “C” student.

Dr. Richard Marlink, the director of the Rutgers Global Health Institute, said you can’t think of it that way, for three reasons:

  • Any vaccine is better than no vaccine;
  • The testing period for both vaccines were different — so it’s not exactly an apples-to-apples comparison;
  • We still don’t know the length of effectiveness of any of the vaccines — is it six months or many years?

Then, there’s this: Those who have spent a lifetime in this field will tell you both numbers are outstanding.

“These are all home-run vaccines,” Marlink said. “You’re looking at the difference between a BMW and a Mercedes. They’re both unbelievably wonderful cars — and both are not just going to get me where I need to go, they’re going to get me there in style.

“This is not the difference between the old Pinto and a Cadillac.”

Marlink, the inaugural Henry Rutgers Professor of Global Health, knows his stuff. If you want Ivy League qualifications, he’s got them, including an undergraduate degree from Brown University and two decades of work at Harvard University, where he spent two decades as the executive director of the Harvard AIDS Institute.

This experience, he said, has taught him that people need to let this pandemic play out before they start making judgments on vaccines based solely on one number.

“We’re just beginning to test these vaccines,” he said. “We don’t know how long the durability is. We just know the initial effectiveness.

“What if one lasts much longer than the other? These are different mechanisms to activate our immune system against the virus. They certainly could have different lengths of effectiveness. We don’t know that yet.”

The numbers themselves could be off, too, Marlink said.

“They were tested in different times and in different places,” he said. “The pandemic has changed and there are variants. Johnson & Johnson tested in South Africa, which is good, because there’s a different variant there. We’re just at the beginning of trying to compare vaccines side by side in the real world.

“Instead of fixating on the number, people should look at these as new and very successful vaccines. With variants happening, we’re going to need to continue to test versions of the same vaccine.”

Marlink even has an answer to the ultimate trick question: Which vaccine is the most effective?

It’s the one that’s in your arm, he said.

“When all this balances out, something like a single-shot vaccine that may have a little bit less efficacy in its percentages may overall be more effective, because it’s going to get into more people’s arms,” he said. “Let’s put it that way. We say in drugs, the best drug is the one people take. It will be the same with vaccines. The one that can get into the most people’s arms will be the most effective.”

Marlink hates to dates himself — see the Pinto reference. But, he said a story from his own childhood explains the issue best of all.

“When I was really small, we just sat in our desks at school and got a sugar cube in our mouth for the polio vaccine,” he said. “We thought it was the best vaccine ever. Now, it wasn’t the only version — there was the Sabin and the Salk vaccines. And they were both effective vaccines. But, over time, we learned which one was more effective and had less serious side effects.

“But, they essentially changed the course of polio. It got rid of it. That’s where we want to go.”