Doctor addresses concerns over lower vaccine efficacy

Posted at 6:00 AM, Feb 17, 2021
and last updated 2021-02-17 08:51:23-05

Now that multiple COVID-19 vaccinations are on, or are soon to be on the market, there's a percentage of efficacy attached to each of them. Pfizer and Moderna are promising about 95% protection after two doses. And Johnson and Johnson is promising 66% after one dose. But what does that actually mean?

"It's not like me, myself, now has 66% immunity. It's more of a population measure," says Dr. Deepta Bhattacharya, University of Arizona College of Medicine.

It comes down to clinical trials. People enroll, they're split into two groups, some get the vaccine and some don't.

"And then you just wait over time, to see how many infections accumulate in this group versus that group," says Bhattacharya. And you just calculate the ratio between those to see what is the efficacy."

Let's go back to that Johnson & Johnson vaccine. At 66% efficacy, it may seem a little low when you compare it to Moderna or Pfizer. But, experts say that's okay.

"Even when it says that the vaccines are dropped to 66% efficacy, no one in those groups is actually getting hospitalized for severe diseases," says Bhattacharya.

And remember, too: 66% efficacy is referring to to the overall results of the clinical trial.

"When it says 66%, it means that when you get that vaccine, there's a 66% chance that you'll have no symptoms at all," says Bhattacharya. "So then the rest of the group will have at least some degree of partial-protection. You're certainly going to get a lot less sick than you would have if you didn't get the vaccine."

We've also heard a lot about those variants of COVID-19 that are popping up around the country. So we wanted to know: how will these vaccines stand up to new strains?

"We're looking at maybe a booster and maybe another one after that later on down the road; it's not the biggest deal in the world," says Bhattacharya. "And again, what we're seeing is that even the people who do get sick with those variants, after they've been vaccinated, aren't getting as sick as you would had you not gotten the vaccine."

So there you have it. Doctors say get the vaccine once it's available to you. And don't worry about the number attached because the pros of getting the shot, far outweigh the cons.

Johnson & Johnson applied for emergency use authorization about two weeks ago. The FDA will make its recommendation at a public meeting on February 26th.