Dr. Richard Pellegrino

On Monday, Moderna announced that its coronavirus vaccine, which like Pfizer is in its third and final clinical trial phase, had shown 94.5% efficacy and that it would be seeking an Emergency Use Authorization with the U.S. Food and Drug Administration “in the coming weeks.”

Baptist Hospital has been participating in Moderna’s clinical trials, under the direction of neurologist Dr. Richard Pellegrino, since August. Enrollment has ended, but the trial will continue for two years.


The trial is double-blind, so neither participants nor physicians know who has been given placebo and who vaccine (the numbers are 50-50). Participants are not exposed to the coronavirus as part of the trial; whether it’s effective or not is based on assumptions that all participants  — who are roughly equally healthy individuals — will be exposed to the virus in the community. If participants in the trial contract COVID-19, the blind is broken and data on whether they received vaccine or placebo is revealed. Moderna’s analysis found that 95 participants (30,000 are enrolled) became infected with the virus two weeks following the second dose of the vaccine, and of those, only 5 had received vaccine. All who developed severe cases had been given placebo.

Pfizer announced yesterday that it had concluded its phase 3 trial, and that its vaccine was proving 95 percent effective beginning 28 days after the first dose. Its data was based on 170 confirmed cases of COVID-19; only 8 had received the vaccine rather than placebo. Observed efficacy in adults over 65 — who will be among the first to get vaccine after health care workers — was over 94 percent, the pharmaceutical company said.


Neither Moderna nor Pfizer reported serious safety concerns.

Pellegrino described how the trial is conducted: Participants at Baptist go through a physical exam and provide informed consent before getting inoculated. They must not have previously had COVID-19. They’re observed for 30 minutes to make sure they are suffering no ill effects before going home. They then keep an electronic diary on how they are faring; this is done by app and participants are to report every day for two years. The doctors, meanwhile, check up on participants with weekly phone calls. At the end of 29 days, participants return, go through health exams again, and get their second shot. They’ll return for checkups; in all, they will visit the medical team six times.


Enrollees in the Moderna trial range from 18 and up. Pellegrino said he was not allowed to provide the total number enrolled in the study, but that it was “significant.”  

Like Pfizer, Moderna is using messenger RNA to protect the body against COVID-19. The messenger codes for a sticky protein that the virus carries on its spikes, and is delivered in a “lipid sphere” to the body. Once penetrated, the cell will make the spike protein and send the protein to its surface, where it will be recognized as foreign and be attacked by the body’s immune system. It takes the body two or three weeks, Pellegrino said, to make enough antibodies to wipe out the protein, so it will take several weeks for immunity to be achieved. The body is then sensitized to the protein, and antibodies and T-cells will more quickly do the job of disarming it.

Not everyone will be protected. Pellegrino said it’s important for many COVID-19 vaccines employing a number of strategies to be developed to address variations among individuals. Baptist will run four or five more vaccine trials; interested persons should may learn more at arkansascovidvaccine.com.

Moderna received $1 billion from the federal government’s Operation Warp Speed program to develop its vaccine, which it calls mRNA-1273, and another $1.5 billion in exchange for 100 million doses if the vaccine proves safe and effective.