Written by Sarah Wornow ‘23
Edited by Geat Ramush ‘23
As of November 2020, there are eleven major COVID-19 vaccines in Phase 3 clinical trials. These vaccines come from a diverse set of interdisciplinary teams: from pharmaceutical giants such as Johnson & Johnson, Pfizer, and AstraZeneca, to up-and-coming biotech startups Moderna and Novavax, to international companies from China, Russia, and Australia. Arguably some of the most promising clinical trial results have come from the joint Pfizer, BioNTech, and Fosun Pharma vaccine, known as BNT162b2. Early results from their Phase 3 trial has shown the vaccine is more than 90% effective in preventing COVID-19 . With these promising results, the vaccine is expected to be mass-produced and distributed globally. By the end of 2021, Pfizer expects more than 1.3 billion doses of the vaccine to be manufactured [2, 3].
BNT162b2 is an mRNA vaccine that has shown mild side effects, including headaches and fatigue, and requires a booster shot for increased efficacy. Once injected, the mRNA from the vaccine is transcribed and translated by the patient’s cellular mechanisms to produce the SARS-COV-2 spike protein and present it outwardly on cells. Because this spike protein is considered foreign to the host’s body, immune cells recognize and neutralize it. The patient’s immune system is now primed for a real exposure to the viral SARS-COV-2 strain, and the patient is considered protected.
Despite strong positive results of earlier clinical trials, and millions of dollars invested by various governments to ramp up production, mass distribution of the Pfizer vaccine may be unattainable for one main reason: the ultracold temperature at which the vaccine has to be stored at. mRNA vaccines are a relatively recent discovery, with no licensed vaccine currently utilizing this technology . As opposed to traditional vaccines, which require normal refrigeration, mRNA vaccines need to be stored under extremely cold conditions. In order to deliver mRNA strands, which are extremely unstable, to a patient’s cells, a lipid nanoparticle must encase the strands. These lipid nanoparticles are very sensitive to heat, and the only way to stabilize them is through ultracold storage . In comparison to Moderna’s mRNA vaccine, which requires cold storage at -4℉, Pfizer’s vaccine requires storage at -94℉, which is colder than most industrial freezers, and the Pfizer vaccine can only last up to 6 hours at room temperature [6, 7]. Most vaccination sites, including hospitals, clinics, doctor’s offices, and pharmacies, don’t have the ultracold freezers necessary to preserve the vaccine. Instead, only large scale hospitals and pharmacies have the freezers needed to maintain cold temperatures. As such, the vaccine would primarily be shipped to these locations.
Not only do vaccination sites lack the freezing requirements needed, but also shipping companies are currently unable to ship mass quantities of ultracold vaccines. Pfizer has partnered with the UPS to develop ultracold shipping containers that can hold the vaccine at the required temperature. The packages utilize cold-resistant glass vials to hold the vaccine and dry ice to maintain cold temperatures. Although this may seem like a sustainable solution, the US presently has a shortage of both dry ice (due to a shortage in CO2) and cold-resistant glass . Mass shipping using these containers would cause a huge strain on the supply chain and likely would require investments of billions of dollars.
Evidently, there are multiple issues with attempting to mass distribute the Pfizer vaccine, including a lack of ultracold freezers at vaccination sites and a shortage of dry ice and cold-resistant glass. In addition, everyone receiving this vaccine would have to also get a booster shot for full efficacy, meaning double the number of vaccines would have to be shipped. Though the Pfizer vaccine ultimately doesn’t seem like the main COVID-19 vaccine that everyone will receive, it will still most likely be able to reach many people through larger vaccination sites.
To keep updated on COVID-19 vaccine development, check out the New York Times Vaccine Tracker.
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 Harris R. Pfizer COVID-19 Vaccine Won't Be Ready By Election Day. NPR [Internet] [Cited 2020 Oct 17]. Available from: https://www.npr.org/sections/coronavirus-live-updates/2020/10/16/924502362/pfizer-covid-19-vaccine-wont-be-ready-by-election-day
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 Image Available from: https://commons.wikimedia.org/wiki/File:Vacina_-_image_2.jpg