COVID-19 Resources

Moderna COVID-19 Vaccine Trial Showing 95% Efficacy Nationwide

Nov. 18, 2020

Here’s how the COVID-19 vaccine works - and how it’s different from others.


Since June, clinicians at UC Health and the University of Cincinnati College of Medicine have been one of nearly 90 sites nationwide taking part in the Moderna Phase 3 vaccine trial for COVID-19, enrolling 185 participants from throughout our region.

And on Monday, Nov. 16, Moderna released data showing a 95% effectiveness in the 30,000 total Americans participating in the trial.

“There is still so much to do and more data to generate, but hopefully this signals the beginning of the end of the pandemic.” Carl Fichtenbaum, MD Medical Director, Trial Co-Investigator & Infectious Diseases Physician

It is a monumental achievement for UC Health’s team and the trial at large.

“I am very proud of UC, UC Health and our entire team. There is still much to do and more data to generate, but hopefully this signals the beginning of the end of the pandemic,” said Carl Fichtenbaum, MD, co-investigator and medical director of the study; professor in the Division of Infectious Diseases in the Department of Internal Medicine at the UC College of Medicine; and a UC Health physician.

"A multitude of individuals at UC, UC Health and the Greater Cincinnati area came together to help our community be part of this important effort to find a solution to the COVID-19 pandemic,” said Maggie Powers-Fletcher, PhD, D(ABMM), co-investigator of the study and assistant professor in the Division of Infectious Diseases at the UC College of Medicine.

“This contribution to science is essential, regardless of the findings of the study, but the positive data released today regarding the vaccine's efficacy and safety is incredibly encouraging," she continued.

The Moderna COVID-19 vaccine, called the mRNA-1273 vaccine, is different from others in that it doesn’t contain strains of the virus that signal an immune response. (This is how many other vaccines work, like the ones for chickenpox and the flu.)

Here’s how the Moderna vaccine works: When you get COVID-19, your body makes a specific protein to fight the infection. The vaccine tells your body to create these proteins. Your body doesn’t know the difference, so it triggers the immune system to protect you — without ever being exposed to the virus.

This new vaccine was administered to 185 participants at UC and UC Health as part of the national Phase 3 trial.

In the third phase of a trial, researchers study how well the vaccine works by giving it to a large group of people and seeing who contracts COVID-19. This phase is meant to prove that a new vaccine or medication is indeed effective — or discover that perhaps, it’s not.

“We do clinical trials because we truly don’t know the answer, such as whether the vaccine will work or not. Based on the information that we had, we hoped the vaccine would work but we don’t always get it right,” said Brett Kissela, MD, MS, Albert Barnes Voorheis Chair and professor in the Department of Neurology and Rehabilitation Medicine, senior associate dean for clinical research at the UC College of Medicine and chief of research services at UC Health — and a participant in the Moderna trial. “That’s the process of science. We have to do a trial to test if it works, while closely watching to make sure it is safe.”

In the trial, participants received two doses of a vaccine — either the study dose or a placebo.

Having a control group of people who received the placebo allows researchers to understand how well the experimental vaccine protected individuals. If significantly more people in the placebo group got COVID-19 than those who received the vaccine, then scientists know the vaccine helped protect against infection.

“Part of enrolling in a trial is being altruistic,” Dr. Kissela said. “I know that I’m part of a trial that’s going to get to the solution, even if I get the placebo and it doesn’t benefit me personally.”

Participants in the trial will continue to be monitored for a total of 25 months.

At UC Health, the first dose of the vaccine was administered on Aug. 25, and the final participant was enrolled on Oct. 23. UC and UC Health enrolled 185 people overall — 49% of whom were non-white and/or Hispanic.

Moderna and Pfizer, whose COVID-19 vaccine has also showed promising early data, are expected to apply for FDA emergency use authorization this year to begin distributing vaccines to the general public, beginning with at-risk populations.