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Comparing COVID-19 Vaccine Candidates from Pfizer, Moderna
Both Moderna and Pfizer’s lead mRNA COVID-19 vaccines were over 90% effective in clinical trials, but they have a few major differences that must be addressed before being FDA approved.
Since the start of the pandemic, pharmaceutical companies have been racing to develop a COVID-19 vaccine. Now, two vaccine candidates – one from Pfizer and the other from Massachusetts-based Moderna – are pulling ahead.
Both candidates leverage mRNA technology, which could have an impact on serious diseases, such as COVID-19, due to its shorter manufacturing times, greater effectiveness, and inexpensive production cost.
Messenger RNA directs the body’s protein production in a more targeted way, presenting an opportunity to combat serious diseases in a way not possible before.
But despite their similar production technologies, Pfizer and Moderna’s vaccines are showed differences in clinical trial results and storage needs.
The companies also have varying supply and distribution plans as well.
In the following article, PharmaNewsIntelligence goes in depth about Pfizer’s and Moderna’s respective mRNA-based COVID-19 vaccines and explores their similarities and differences across the board.
Clinical Trials
Both COVID-19 vaccine candidates have proven to be highly effective based on Phase 3 clinical trial data. But the vaccines have been on slightly different paths.
Moderna
At the end of January, two months before COVID-19 began rapidly spreading throughout the US, Moderna committed to manufacturing mRNA-based coronavirus vaccines in collaboration with the Vaccine Research Center of the National Institutes of Health’s NIAID, and with funding from The Coalition for Epidemic Preparedness Innovations (CEPI).
And then in April, Moderna received $483 million from the Biomedical Advanced Research and Development Authority (BARDA) to boost these efforts.
After months of clinical trial testing, Moderna announced that its mRNA COVID-19 vaccine candidate, mRNA-1273, proved 95 percent effective in a Phase 3 clinical trial earlier this week.
mRNA-1273 met statistical pre-specified in the study protocol for efficacy in most US participants, the company reported.
Researchers first analyzed 95 cases, all of which showed a point estimate of vaccine efficacy of 94.5 percent. The second endpoint was severe COVID-19 cases, of which there were just 11.
Notably, the 11 severe cases were in the placebo group and not the mRNA-1273 group.
Pfizer & BioNTech
At the end of April, Pfizer partnered with BioNTech to produce mRNA-based COVID-19 vaccines, and three months later, the companies launched a global Phase 2/3 clinical study to evaluate their most promising COVID-19 vaccine candidate, BNT162b2.
Most recently, the companies announced that BNT162b2 demonstrated evidence of efficacy against coronavirus in participants without prior evidence of SARS-CoV-2 infection.
Similar to Moderna’s vaccine, BNT162b2 was found to be over 95 percent effective in preventing COVID-19 in these participants and elicited no serious side effects.
But there were two major differences between the companies’ individual vaccines.
First, Moderna enrolled just over 30,000 participants, while Pfizer enrolled over 45,000 participants.
And while both companies spaced vaccine dosages out 28 days apart, Moderna analyzed its participants 14 days after administration, while Pfizer measured efficacy just seven days after.
Therefore, participants vaccinated with Moderna’s vaccine had seven additional days to develop any immunity before they were counted.
Storage of the COVID-19 Candidates
While there were a few minor differences in the clinical trials, the major variance lies in the storage of each candidate.
Long-term storage of Pfizer’s product must be at -112 degrees Fahrenheit to remain effective. This temperature requires special freezers usually found in research labs and hospitals.
But while Pfizer is developing deep freeze “suitcases” that can be sealed and are safe for shipment in non-refrigerated trucks, these suitcases could create challenges for hospitals, pharmacies, and outpatient clinics that have to administer the vaccines to US citizens.
Additionally, the company’s vaccine can only be stored in the refrigerator for five days.
In contrast, Moderna’s vaccine can be stored at 36 to 46 degrees Fahrenheit and can last nearly 30 days in the fridge.
Specifically, mRNA-1273 can remain stable at four degrees Fahrenheit for nearly six months, at refrigerated conditions for up to 30 days, and at room temperature for up to 12 hours, Moderna stated in a press release.
“We believe that our investments in mRNA delivery technology and manufacturing process development will allow us to store and ship our COVID-19 vaccine candidate at temperatures commonly found in readily available pharmaceutical freezers and refrigerators,” Juan Andres, chief technical operations and quality officer at Modern, said in the release earlier this week.
The major storage differences between two similarly structured vaccines may be because of how the vaccines’ synthetic mRNA is packaged, according to Paula Cannon, an associate professor of microbiology at the University of Southern California's Keck School of Medicine.
The refrigeration conditions may have to do with how the mRNA was manufactured and stabilized.
But many hospitals and academic medical centers already have the freezers needed to effectively store Pfizer’s vaccine because they used them to store lab diagnostic materials and biologic samples.
“More than 50% of our members already had them on hand,” Azra Behlim, senior director of pharmacy sourcing at Vizient, said in a recent article.
Notably, Vizient works with over 60 percent of all hospitals in the US.
Distribution & Supply Plans
Like many other pharmaceutical companies running the COVID-19 vaccine race, Pfizer and Moderna have developed distribution plans alongside drug development in order to get an approved vaccine into the hands of providers as soon as possible.
In mid-August, for example, HHS and the Department of Defense (DoD) announced an agreement with Moderna for large-scale production and nationwide delivery of 100 million doses of mRNA-1273 in the US.
Under the agreement, Moderna will manufacture the vaccine doses while clinical trials are underway. The federal government will own the doses and will be able to acquire up to an additional 400 million doses of mRNA-1273.
The HHS-Moderna agreement also includes fill-finish manufacturing in US-based facilities, which ensures vaccine doses are packaged and ready to ship immediately once a vaccine shows success in clinical trials, HHS said.
mRNA-1273 would be available to US citizens at no cost. But generally, government-purchased vaccines allow healthcare professionals to charge for the cost of administering the vaccine.
Overall, Moderna said it can make 20 million doses for the US this year, and between 500 million and 1 billion next year.
Pfizer and BioNTech have also been building their manufacturing capacity.
At the end of July, HHS and the DoD announced an agreement with Pfizer for large-scale production and nationwide delivery of 100 million doses of BNT162b2.
Under the agreement, the government will pay Pfizer and BioNTech $1.95 billion upon the receipt of the first 100 million doses.
The delivery will take place following the vaccine’s successful manufacture and approval.
And under the terms of agreement, the US government can acquire an additional 500 million doses for Americans.
In the US, Pfizer plans to have made 50 million doses by the end of the year and 1.3 billion doses in 2021.
At the end of August, HHS and the DoD tapped McKesson Corporation to help distribute future COVID-19, such as Pfizer’s and Moderna’s, as well as related supplies needed to successfully administer the drug.
If these experimental COVID-19 vaccines gain approval from FDA, they will be the first-ever authorized vaccines that use mRNA. This new development would not only help to combat the ongoing pandemic, but could also uncover an entirely new line of vaccines against various diseases.
