Like Pfizer announced recently, Moderna Therapeutics has released preliminary results for its COVID-19 vaccine. And like Pfizer, Moderna’s data is very exciting but, and there’s always a but, the data has not been peer-reviewed or analyzed independently.
To be fair, I’ve been highly critical of Moderna because of their lack of transparency and the overreliance on press releases to boost their stock prices. For many pharmaceutical companies, like Merck or Pfizer, vaccines make up only a tiny portion of their revenue and profits. For Moderna, their whole reason for existence is vaccines. So if they have a blockbuster vaccine, their stock prices skyrocket.
That being said, there are some reasons to get somewhat more excited about the Moderna COVID-19 vaccine over the Pfizer one. So, let’s take a look.
What is the Moderna COVID-19 vaccine?
Like Pfizer’s vaccine, the Moderna COVID-19 vaccine is an mRNA vaccine that seems to be The 2020 vaccine technology.
These mRNA vaccine technologies rely upon an mRNA, or messenger RNA, molecule to induce an immune response. Normally, mRNA molecules in the cell correspond to DNA sequences in genes and carry that information to be “read” by a ribosome to produce a protein.
When an mRNA strand exits the nucleus and enters the cytoplasm, it attaches to ribosomes, and this is where protein synthesis progresses. The ribosome reads the base sequence of the mRNA, three bases at a time. Each three-base triplet, called a codon, specifies a particular amino acid, except for a few with regulatory functions (e.g., UGA =“Stop!”).
If the first three-base codon is AUG, then a molecule of the amino acid methionine is brought into place. If the next triplet is AAA, that brings in the amino acid lysine. The methionine and lysine molecules are attached together. The next triplet is, say, GCC, and that brings in alanine, which is attached to the lysine. The ribosome has read nine bases, AUGAAAGCC, and compiled a short chain of three amino acids, abbreviated Met-Lys-Ala, or MKA (see amino acid abbreviations here).
The ribosome continues reading all of the mRNA bases until it hits a stop signal—which is also a triplet codon such as UGA—and the now long chain of amino acids falls loose. This chain may be a functional protein immediately, or, more usually, it might undergo some additional post-translational processing by enzymes to become active.
Moderna’s mRNA vaccine technology relies on a specific mRNA to kickstart the endogenous production of proteins that are similar to some of the SARS-CoV-2 antigens. These antigens will trigger the body’s adaptive immune system to produce antibodies effective against the actual target, in this case, the S-protein or spike on the SARS-CoV-2 virus.
In other words, instead of injecting a live-attenuated vaccine, like the measles vaccine which contains weakened measles virus, the Moderna COVID-19 vaccine injects mRNA fragments that are selectively delivered to cells to produce the viral antigens (but not the whole virus, of course).
Despite the claims of some really outlandish pseudoscience in the anti-vaccine world, this mRNA vaccine will not “hijack” your DNA, self-replicate to turn you into a huge coronavirus, nor mutate into a new form of the virus. It is self-limiting because the mRNA molecule does not replicate and it is quickly destroyed after it produces the protein.
The mRNA technology for vaccines is very new, Moderna has been working on them for years, never getting a vaccine past a phase 2 clinical trial (in a normal world of vaccine development, this just means everyone is taking their time). Because it is a new technology, I wish that we could take a much longer time to analyze it, but a single day’s delay in a vaccine could mean thousands of deaths.
Let me give the giant, critical caveat – these results have not been peer-reviewed. They have not been published in a respected biomedical journal. It has not been reviewed by independent groups such as the Vaccines and Related Biological Products Advisory Committee (VRBPAC), which is made up of leading scientists who may require further testing or could even reject an application for a vaccine.
Moderna reported that a preliminary analysis showed its experimental coronavirus vaccine is nearly 95 percent effective at preventing illness, including severe cases of COVID-19. That is slightly better than the results from Pfizer. There were 90 cases of COVID-19 in the placebo group and 5 in the Moderna COVID-19 vaccine group two weeks after the second vaccination.
In addition, Moderna claimed that:
The interim analysis included a concurrent review of the available Phase 3 COVE study safety data by the DSMB, which did not report any significant safety concerns. A review of solicited adverse events indicated that the vaccine was generally well tolerated. The majority of adverse events were mild or moderate in severity. Grade 3 (severe) events greater than or equal to 2% in frequency after the first dose included injection site pain (2.7%), and after the second dose included fatigue (9.7%), myalgia (8.9%), arthralgia (5.2%), headache (4.5%), pain (4.1%) and erythema/redness at the injection site (2.0%). These solicited adverse events were generally short-lived. These data are subject to change based on ongoing analysis of further Phase 3 COVE study data and final analysis.
Those side effects are “normal” for most vaccines since it is just indicative of an immune response to the vaccine (though, we all know that the anti-vaxxers will be abusing this for years to come).
Furthermore, there are some advantages of the Moderna vs the Pfizer COVID-19 vaccine. As I mentioned before, the Pfizer vaccine must be stored in a medical-grade deep freezer, at an average of -75ºC (or -103º in barbarian measurements). Those types of freezers are not generally in most medical facilities.
Oh the other hand, the Moderna vaccine can be stored for up to 30 days in a refrigerator and up to six months in a freezer.
This all looks good, but…
And here it is, the “buts”
Let me just list these “buts,” because there are a few:
- The Moderna COVID-19 vaccine requires two doses to be effective (like Pfizer’s vaccine). This not only reduces the supply of vaccine doses by half, it also means some people will refuse to get the second dose.
- The “effectiveness” is after 2 weeks post the second vaccine. We don’t know enough about the long-term immunity to the disease. We don’t know how long it might take for the immunity to wane. What if this vaccine is only effective for three months, but people are dancing in the streets because they think they’re immune? That will be a disaster. I assume that Moderna will continue post-marketing studies, which the FDA will require, but it takes time to understand if there’s an issue.
- Safety issues are always overexaggerated by anti-vaxxers, but that being said, I would prefer a lot more transparency into some of these more severe adverse events. Are they linked to the vaccine, or, like most of these, are not causally related?
- The data does not clearly lay out how many patients and cases were found in the most at-risk groups – seniors, people of color, and those with co-morbidities. If there are only one or two cases in each group, the statistics will be meaningless. That’s why we need a lot more analysis of this “preliminary” data.
- Given that this is a new vaccine technology, I would prefer a lot more careful short- and long-term analysis of safety. This would not be required to assuage my concerns but to those of the vaccine-hesitant groups.
- Moderna (and frankly, Pfizer) have not provided very good science describing why there are those who got the vaccine but still contracted the disease.
- There is no data describing what happens to patients who receive the vaccine but already had anti-COVID-19 antibodies. There’s probably nothing to be concerned about, but I’d rather know what the data says.
- Moderna is claiming a 95% reduction in risk of the disease, similar to Pfizer’s numbers, but I cannot determine how many patients were in each arm of the clinical trial (at the time of providing the results). They’re giving us a risk reduction based on 90 cases in the placebo group and 5 in the vaccine group. But if the placebo group is 2X larger than the vaccine group, it could mean that the effectiveness is substantially lower. That’s why we cannot keep having this peer-review by press release, we need actual data to review.
- We have no information about what effect these vaccines have on asymptomatic carriers. What if this has no effect, then we’ve done almost nothing to prevent the disease?
- The data provided in the press release do not provide enough information to assess whether or not the vaccine protects against infection or only against illness. Additionally, we do not know whether the vaccine altered the severity of disease in patients who became unwell having received the Moderna COVID-19 vaccine.
- Similar to Pfizer, Moderna will be seeking an Emergency Use Authorization (EUA) in the USA for use in groups who are most in need of protection from COVID-19. However, we should be wary of any EUA (anywhere in the world) where there hasn’t been a thorough review of the data.
My concerns are very similar between the Pfizer and Moderna mRNA vaccines, specifically about the quality and transparency of data. I just wish they would release all of the data, independent of the FDA commissioner, to the VRBPAC, who would then release a detailed, unbiased report to the country. Although President-elect Joe Biden has not said it specifically, he might be considering this group of scientists to examine these vaccines.
I am probably a bit more excited about the Moderna vaccine because it will be easier to distribute widely. But I am more suspicious of the motives and goals of the Moderna executives, so when they don’t release data, it makes me much warier of what they’re selling.
At this time (16 November 2020), Pfizer and Moderna have built a lead in getting a vaccine to market. There are others like the
Soviet Russian Sputnik V vaccine which got approval with hardly a clinical trial (do not trust that vaccine) and Astra-Zeneca/Oxford which had its own hiccups.
As I wrote earlier, there are about 10-15 other vaccines in phase 3 clinical trials, so we might have many choices of vaccines by late 2021.