On Thursday, a panel of outside experts participated in a day-long review of the data on the Moderna COVID-19 vaccine. Though this was a somewhat different set of experts (with considerable overlap) from those who reviewed the Pfizer vaccine last week, many of the same questions came up over the course of the day. Unlike the Pfizer vaccine, Moderna only asked for an emergency use authorization (EUA) in patients over 18, so a good deal of the concern that occurred near the end of the Pfizer vote that focused on younger patients was avoided.
At the end of the day, the panel eventually voted in favor of approving the vaccine by a vote of 20 to 0 … though not before a technical glitch led to a false start after the experts were temporarily asked to vote on the Pfizer vaccine that is already in distribution. A single expert voted to abstain. With this vote, the Moderna vaccine will move to the Food and Drug Administration (FDA) and Centers for Disease Control and Prevention (CDC) for final approval. It is very likely to follow the same steps that Pfizer did last week. That means that this weekend a second vaccine rollout could begin, and by Monday the first U.S. patients could be receiving the Moderna vaccine.
As in the previous review, the day included a presentation from the FDA and a separate presentation from Moderna, both of which were followed by question and answer sessions. The biggest concern generated by this discussion was not directly about the safety or efficacy of Moderna’s vaccine, but over the issue of how Moderna intends to handle volunteers in their trial in the future. Where Pfizer intended to reveal whether or not a volunteer had received vaccine or placebo only on request, and only at a time when the volunteer might gain access to the vaccine, Moderna appears to be much more aggressive in their “unblinding.” In essence, Moderna intends to promptly reveal the status to all the volunteers so that those who got placebo can seek vaccine as soon as possible. The concern from the panel is that this limits the ability of the study going forward to look for long-term issues since there will no longer be a “control group.”
Another discussion that came up this week that was largely avoided during the Pfizer debate was focused on concern that the FDA was issuing emergency use authorizations too frequently on vaccines in the future, and that the question should not be worded so broadly in allowing the vaccine to be administered to anyone over 18 rather than explicitly making it available only to groups that were at high risk. Some of the participants worried that by using EUAs with this broad authority, the FDA had little incentive to come back for a lengthy review process required for full approval. It was primarily for this reason that one expert abstained.
The reviewing group found the Moderna study to be “well organized” and “very thorough.” They also appreciated the way in which Moderna tested patients for COVID-19 at intervals throughout the study rather than simply waiting for symptoms to appear. This change was enough to net the vaccine the vote of one expert who voted against the Pfizer vaccine a week earlier. Others felt safer in coming on board because the question of whether the vaccine was safe for patients under 18 was avoided.
Like the Pfizer vaccine, Moderna is using mRNA contained in lipids. These two vaccines represent a wholly new approach to vaccine development. Should they prove safe and effective over an extended period, this technology could come to dominate the field. Moderna’s vaccine was developed within 48 hours from the point when their team first obtained the genetic template for the virus.