The results were based on the first interim efficacy analysis conducted by an external and independent Data Monitoring Committee (D.M.C.), a group of experts that oversees U.S. clinical studies to protect the safety of volunteers.
The D.M.C. evaluated the drug's high efficacy through comparison of clinical trial data between the two participant groups: vaccine and placebo. Researchers found that of the nearly 44,000 participants, 94 had become infected with the virus. After splitting the infected individuals between the two trial groups, researchers found that the vaccine had an efficacy rating of above 90% at seven days after the drug's second dose.
While the two companies did not release specific breakdowns, nearly all infections most have occurred in the placebo group to rate that high of an efficacy.
Based on the interim data analysis, protection from the virus was achieved in trial participants 28 days after initial vaccination, with Pfizer's drug requiring two doses. The companies noted, however, that the final vaccine efficacy percentage is subject to change as additional data continues to be collected for the ongoing Phase III trial.
If the pair's vaccine is granted emergency use approval, the companies estimate that they can deliver 50 million doses by the end of this year, which will be enough to vaccinate 25 million people. The companies expect to produce up to 1.3 billion doses in 2021.
While these extraordinary results are welcome in a time when coronavirus outlooks remain bleak, there are still many questions that the vaccine's publicly released data has failed to answer, such as how long the drug will provide immunity and what is the vaccine's safety profile across diverse groups.
Other Vaccine Statuses
Of the dozens of vaccine clinical trials being conducted worldwide, there are currently four frontrunners in late stage Phase III studies: AstraZeneca
Of the frontrunners, Pfizer and Moderna's candidates are expected to be the companies to receive the first regulatory approvals due to their slight lead advantage over the other drugmakers. Pfizer's high interim efficiency rating also boosts the chances of Moderna's candidate being highly effective, for the two use the same vaccine technology called messenger RNA (mRNA). Moderna's vaccine has also demonstrated similar or better results when compared to Pfizer's early stage studies.
Moderna announced last month that its trial has completed participant enrollment, with the vaccine also anticipated to be approved for public use in December. AstraZeneca's vaccine could also passed regulatory approval by the end of the year, while Johnson & Johnson's candidate is expected in early 2021.