A COVID-19 Vaccine: What’s Been Done and What’s to Come


The coronavirus (COVID-19) pandemic has completely taken the world aback, forcing individuals to alter their usual ways of life. From abruptly transitioning to Zoom classes in March to requiring masks in virtually all public spaces, COVID-19 has affected all facets of society, which has paved the way for what some dub the “new normal.” However, it’s clear that many people are dissatisfied with these unprecedented circumstances, as they have led to significant lifestyle restrictions, record-high unemployment levels, and negative mental health implications.1 With cases in the US at an all-time high nine months after the pandemic was declared a national emergency, many are left wondering: when, if ever, will life go back to normal again? 

The answer greatly depends on the development and distribution of a coronavirus vaccine. This process usually takes place over the span of several years.2 However, the US government, in partnership with the private sector, has initiated a multibillion-dollar plan known as Operation Warp Speed (OWS), which aims to accelerate the production and delivery of safe and effective COVID-19 vaccines to the general public.3 In June 2020, the White House named five vaccine candidates that would most likely meet the timeline of OWS. These include Moderna’s mRNA-1273, AstraZeneca and Oxford University’s AZD-1222, Johnson & Johnson’s JNJ-78436735, Merck’s multiple candidates, and Pfizer and BioNTech’s BNT-162b2.4 

Among the first to announce promising results related to a coronavirus vaccine was the American pharmaceutical company, Pfizer, along with its German partner, BioNTech. Their vaccine employs mRNA technology, in which the body’s cells translate genetic information from an mRNA sequence to produce antigens in the form of the SARS-CoV-2 full-length spike glycoprotein (S).5 These antigens are subsequently exhibited on the surface of the body’s cells, initiating an immune response that enables the production of antibodies against the glycoproteins.6 After successful early clinical trials in animals, Pfizer and BioNTech proceeded to Phase 3 in July 2020. This stage is especially vital in vaccine development, as it tests the efficacy of the immunization on a large population. In Phase 3 of the companies’ clinical trials, half of the 44,000 participants received the vaccine, and the other half received a placebo of saltwater.7 Out of the 44,000 participants in the study, 94 became sick.7 Although it was not indicated how many of the sick participants had received the vaccination, Pfizer released preliminary data based on these results on November 9, indicating a vaccine efficacy rate above 90%.8 At the time of this declaration, however, the study had not yet been concluded. Only 94 COVID-19 cases had been identified, but a total of 164 cases needed to be detected in order to complete the trial.9 

Pfizer is one of the world’s largest pharmaceutical companies. Its headquarters are located in New York City. (Wikimedia Commons)

Pfizer and BioNTech ultimately became the first companies to release complete results of their coronavirus vaccine trials after they officially concluded Phase 3 of their study on November 18. They announced that their vaccine, BNT-162b2, turned out to be 95% effective against COVID-19, and resulted in no serious side effects.10 One of the main concerns surrounding the effectiveness of the vaccine was its potential for success amongst older adults. However, results indicate the vaccine being 94% effective in this age group.11 This news bodes very well in the grand scheme of the darkness and uncertainty that has come with a pandemic that has taken the lives of more than 1.5 million people. The US Food and Drug Administration (FDA) standards for a successful COVID-19 vaccine require a 50% efficacy rate, and Pfizer and BioNTech’s BNT-162b2 clearly exceeds this threshold by a wide margin.12 Thus, on November 20, the companies submitted an emergency use authorization request to the FDA, in addition to submitting other rolling submissions worldwide, including Australia, Canada, Europe, Japan, and the United Kingdom.13 The US FDA plans to review the authorization of this vaccine on December 10. Meanwhile, on December 2, Britain became the first country in the world to authorize the use of Pfizer and BioNTech’s COVID-19 vaccine. 

These advancements undoubtedly mark major milestones in the midst of seemingly never-ending coronavirus chaos. However, the companies’ vaccine poses significant logistical challenges in terms of reaching patients. One major obstacle is temperature—the vaccine must be kept frozen at -70oC, making distribution much less convenient and much more expensive.14 The reason as to why this vaccine must be kept ultracold goes back to its mRNA technology—mRNA is fragile and easily degraded.15 To ensure that the mRNA is intact when it reaches patients, it must be stored at an extremely low temperature. This emerges as a serious challenge to an essential part of controlling the pandemic, as the availability of transportation with freezers is limited. The finite supply of freezer trucks, trains, and planes is already being used to transport other goods and essentials, like food and medicine.15 Therefore, the immediate threat of the pandemic will require trade-offs to be made for adequate vaccine distribution. With hopes that these hurdles will be effectively addressed, Pfizer and BioNTech expect to produce up to 50 million doses by the end of 2020 and up to 1.3 billion doses by the end of 2021.16  

Shortly after Pfizer and BioNTech released their trailblazing news, Moderna, a biotechnology company based in Cambridge, Massachusetts, announced similarly hopeful results on November 16. Moderna’s vaccine candidate against COVID-19, mRNA-127, resulted in a 94.5% efficacy rate during the preliminary analysis of its Phase 3 trial, also known as the Coronavirus Efficacy and Safety Study (COVE) study.17 The COVE study is a collaboration between the National Institute of Allergy and Infectious Diseases (NAID) and the Biomedical Advanced Research and Development Authority (BARDA). It has enrolled upwards of 30,000 participants, and the first interim analysis revealed 95 cases of COVID-19 amongst volunteers, with 90 of these cases occurring in the placebo group, thus indicating a vaccine efficacy of 94.5%.18 Later, on November 30, Moderna announced a primary efficacy analysis of its Phase 3 COVE study, which revealed a 94.1% vaccine efficacy against COVID-19 and a 100% vaccine efficacy against severe COVID-19.18 No serious safety concerns related to mRNA-1273 were observed during the Phase 3 trial.19 In addition to these reports, Moderna requested an emergency use authorization (EUA) from the US FDA on November 30, and they are expected to hear back on December 17.18 

Moderna’s vaccine employs mRNA technology similar to Pfizer and BioNTech. Despite the similarities in development, Moderna presents a vital advantage in vaccine distribution. For shipping and long-term storage, mRNA-1273 must be kept at -20 oC, which is a standard temperature for freezers.19After thawing, it must be stored between 2oC and 8oC for up to 30 days, which is also a standard temperature range for refrigerators.19 These conditions are much more logistically feasible compared to BNT-162b2—but why is this the case when the vaccines utilize similar technologies? According to Moderna spokesperson Colleen Hussey, the answer lies in two factors. One, she explains, has to do with the vaccine’s “particular nanoparticle properties and structure.”20 The other reason is experience. Moderna has already developed ten mRNA vaccine candidates.20 Distributing Moderna’s vaccine to large populations will therefore be an easier task. However, the availability of more than one vaccine with such high efficacy rates provides a silver lining during the nation’s public health crisis. 

With many people eager to receive a COVID-19 immunization, the question of who will get the vaccine first emerges as a prominent topic. On December 1, the Advisory Committee on Immunization Practices of the Centers for Disease Control and Prevention (CDC) voted to prioritize health care workers and nursing home residents when vaccinations become available later this year.21 These groups comprise approximately 24 million people, meaning that an estimated 48 million doses of the vaccine must be administered to effectively account for everyone.21 Furthermore, the US National Academies of Sciences, Engineering and Medicine (NASEM) has created a five-step guide with suggestions on a fair distribution of COVID-19 vaccines in the United States. The plan is divided into five phases, with Phase 1 consisting of healthcare workers and first responders.22 Phase 2 comprises people with underlying medical conditions that categorize them as high-risk along with older adults in densely populated settings.22 Phase 3 makes up the largest portion of the population with essential service workers at a high risk of exposure, teachers and school staff, people in homeless shelters and prisons, older adults who have not already been treated, and people with underlying conditions that categorize them as moderate-risk.22 Phase 4 consists of young adults, children, and essential service workers at increased risk of exposure, and Phase 5 is everyone else in the population.22 

Groundbreaking advances are being made to control the spread of the coronavirus pandemic. The development of multiple COVID-19 vaccines within such a short time span is a historical achievement in the realm of science and will benefit the lives of billions of people. However, it’s important to note that a vaccine alone will not resolve the current public health situation in the United States. Especially in the midst of a holiday season, it’s inevitable that there are worse days to come. Thus, there must be continued efforts at practicing good personal hygiene, social distancing, and mask-wearing in order to overcome the nation’s biggest challenge of the century. 

Maiya Hossain is a first-year in Davenport College. She is a prospective HSHM major from Ohio. She can be contacted at maiya.hossain@yale.edu



  1. Kochhar, R. (2020, August 26). Unemployment rose higher in three months of COVID-19 than it did in two years of the Great Recession. Retrieved December 06, 2020, from https://www.pewresearch.org/fact-tank/2020/06/11/unemployment-rose-higher-in-three-months-of-covid-19-than-it-did-in-two-years-of-the-great-recession/
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  12. Center for Drug Evaluation and Research. (2020, June 30). Coronavirus (COVID-19) Update: FDA Takes Action to Help Facilitate Timely Development of Safe, Effective COVID-19 Vaccines. Retrieved December 06, 2020, from https://www.fda.gov/news-events/press-announcements/coronavirus-covid-19-update-fda-takes-action-help-facilitate-timely-development-safe-effective-covid 
  13. Pfizer and BioNTech to Submit Emergency Use Authorization Request Today to the U.S. FDA for COVID-19 Vaccine. (2020, November 20). Retrieved December 06, 2020, from https://www.pfizer.com/news/press-release/press-release-detail/pfizer-and-biontech-submit-emergency-use-authorization
  14. Saey, T. (2020, December 03). The ‘last mile’ for COVID-19 vaccines could be the biggest challenge yet. Retrieved December 06, 2020, from https://www.sciencenews.org/article/covid19-coronavirus-vaccine-last-mile-logistics-pfizer-moderna
  15. Saey, T. (2020, November 21). Here’s why COVID-19 vaccines like Pfizer’s need to be kept so cold. Retrieved December 06, 2020, from https://www.sciencenews.org/article/coronavirus-covid-19-why-vaccines-cold-freeze-pfizer-moderna
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  22. Subbaraman, N. (2020, September 17). Who gets a COVID vaccine first? Access plans are taking shape. Retrieved December 06, 2020, from https://www.nature.com/articles/d41586-020-02684-9

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