BOSTON — It is, at the very least, proof that the messenger RNA platform for vaccine delivery is a viable option.
Cambridge-based Moderna reports that an initial review of its COVID-19 vaccine candidate was 94.5% effective at preventing infection with the virus, slightly better than Pfizer’s COVID-19 vaccine contender, which showed initial effectiveness just over 90%.
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Both products use the innovative, and never-before approved for human use, messenger RNA technology to coax the body into producing antibodies to a piece of the virus.
“This is the proof in the pudding,” said Dr. Mark Siedner of Massachusetts General Hospital. “We’re seeing for the first time mRNA vaccines in humans that are appearing to be efficacious in large Phase 3 trials.”
Specifically, the data showed that of 95 confirmed cases of COVID-19 among study subjects, 90 of them were in participants who received not the vaccine, but a placebo. And further, the 11 severe COVID-19 infections seen in the trial fulminated only in placebo patients, suggesting that even if it didn’t prevent infection in everyone, the vaccine could lessen its severity, much as the influenza vaccine often does.
“When the rubber meets the road that’s what we want these vaccines to do,” Dr. Siedner said. “Prevent hospitalizations, prevent deaths.”
Principal investigator Dr. Lindsey Baden, an infectious disease specialist at Brigham and Women’s Hospital, cautioned against reading too much into the results.
“These data are still early. The study is on-going,” he said. “So more data will be accrued.”
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Dr. Baden described the criteria for diagnosis of COVID-19 as a study participant.
“What it meant to become a case is that you had not had COVID before, you completed the vaccine series and then you developed symptoms suggestive of COVID that led to a test that confirmed it,” he said.
Early data is not necessarily suggestive of the way the vaccine will behave once widely distributed, said Dr. Barry Bloom, a specialist in global health at the Harvard School of Public Health. Years of monitoring for efficacy and safety will need to follow, but, he added, it’s an impressive place to start.
“Ninety percent is at the higher end of the protection table by all means,” Dr. Bloom said. “This was the result of a lot of investments, both scientific, over quite a short period of time. And a lot of financial investments that are now beginning to pay off. And I think it’s a great day for science, to be honest.”
“Last year this virus had not been discovered,” Dr. Siedner said. “There are multiple studies in Phase 3 with tens of thousands of people, two of which seem to suggest, preliminarily, greater than 90% protection. That’s like you telling me we discovered fire last year and this year we’re on a rocket ship. I mean it’s a truly remarkable feat of science.”
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