Today, Moderna announced that its coronavirus vaccine appears to be 94.5% effective. It’s the second vaccine candidate (after Pfizer’s, at 90%) to give us an early peek at their phase three results, and once again the news is good, but comes with caveats.
Which vaccine is this?
Moderna’s candidate, like Pfizer’s, is an mRNA vaccine. No mRNA vaccine has yet made it to market, so it was an open question whether this technology is good enough to make a vaccine that works in the real world and not just in the lab. It’s good news that two different mRNA vaccine candidates both work. So far, the approach seems to be a success.
Both vaccines require two doses for full protection, but there’s one huge difference between the vaccines in terms of distribution: Pfizer’s vaccine needs to be kept at ultra-cold temperatures, while Moderna’s can be stored in an ordinary freezer. Moderna’s can also be kept at refrigerator temperature for a month after thawing, if needed.
What do and don’t we know?
So far, both companies have released minimal information about their vaccines. We don’t have full results, and in both cases the trials are not yet completed.
In the Moderna study, of 95 cases of COVID among trial participants, only five were in people who had gotten the vaccine. The other 90 were in the control arm, in which people get fake (“placebo”) shots that only contain saline. (Pfizer’s study had 94 cases, and calculated an efficacy of at least 90%).
Moderna gave a little bit more information than Pfizer, including that 11 cases of COVID were severe, and that all were in people who did not get the vaccine.
Like the other study, this one did not include people who are pregnant or breastfeeding, people who had previously been infected with the coronavirus, or people with some types of serious medical conditions.
Side effects were mild enough for the company to say the vaccine was “generally well tolerated,” with fatigue and muscle aches the most common serious side effects.
How close are we to actually getting a vaccine?
It’s still going to be a while. Moderna and Pfizer both expect to have enough data to apply for approval in the next few weeks, but that’s just the beginning of the process. The FDA will have to consider whether the vaccine has enough potential benefit to outweigh potential risks, and whether there is even enough information to make that decision. You can read more about the process for approval here.
Even if everything goes well, it will be months before most of us can consider getting the vaccine, as it takes time to manufacture enough vaccine for everyone. The New York Times reports that Pfizer thinks they can have 50 million doses available by the end of the year, and Moderna thinks they’ll have 20 million. That means if vaccination starts in January, only a small number of people, likely high-risk workers, will be able to get those vaccines initially. For most of us at lower risk, mid-2021 is the earliest we can expect to line up.
A lot can still happen between now and then. Real-world effectiveness might be a lot less than these initial numbers; the safety profile might be worse; we may have trouble rolling out the vaccine to everybody who wants it; enough people might refuse it and keep us far from the levels of immunity that would be protective for our society as a whole.
But if these vaccines do pan out, this might be the only time we’ll have to go through a holiday season while coronavirus cases are spiking to record numbers. Next year might be better.