On November 9th, 2020, Pfizer and BioNTech announced that their joint COVID-19 candidate two-dose vaccine is more than 90% effective in preventing infection in participants . Although the vaccine will need to be tested further, Pfizer announced that it will be asking the FDA for emergency authorization of its vaccine during the third week of November . By the time it requests this authorization, the company will have collected two months of safety data and administered both doses to 38,955 subjects [1, 2]. Assuming FDA approval, Pfizer aspires to produce 50 million vaccines by the end of 2020 and 1.3 billion the following year . This momentous announcement marks what many hope to be the beginning of the end of this deadly pandemic.
Development of a SARS-CoV-2 vaccine began in January when the SARS-CoV-2 genetic sequence became available to researchers . By studying the genetic sequence, scientists discovered the virus’s spike protein, which enables the virus to access cells and infect humans [3, 4]. Several vaccines currently in development target the spike protein [3, 4]. Many promising coronavirus vaccines are based on the strategy of prompting cells to create their own benign version of the viral protein through mRNA instructions, thereby allowing the immune system to develop a response without undergoing infection . Furthermore, a vaccine should ideally be versatile enough that, if the spike protein evolves, the mRNA sequence can be quickly altered in response .
While Pfizer’s announcement presented what could be the world’s first successful mRNA vaccine, twelve companies are also in the final stages of vaccine development [5, 6]. During the final stage of testing, Phase 3, vaccines are administered to thousands of people . To acquire FDA approval, a vaccine must protect at least 50% of those to whom it is administered; Pfizer’s closest rival in this race, Moderna Therapeutics has recruited 30,000 participants into their Phase 3 study but has yet to publish the results of their trials, though analysis is ongoing [5, 6]. Other companies, such as Zydus and CureVac, are in the midst of Phase 2 development, with the former aiming to enter Phase 3 in December .
Though the reported success of Pfizer’s product is promising, many warn that the road to FDA-approval and vaccine distribution will not be so smooth . Additionally, the full efficacy of Pfizer’s vaccine is unknown. Despite the large number of study participants, it is so far unclear whether the vaccine works better for mild cases or more severe ones, what effect it could have on the elderly, and how long it would provide immunity . Even if the answers to these questions are satisfactory, the FDA could choose to focus on a competitor’s vaccine, depending on the success of other trials .
Assuming that a vaccine receives FDA approval soon, the road to distribution is also a long one. Successful dissemination would be contingent on the cooperation of various entities: the vaccine manufacturer, supplies manufacturers who would produce syringes and needles, government agencies, and the overall public health community . Compounded with the fact that millions of people are hesitant to receive a vaccine, it may be quite a while before the threat of COVID-19 fades from public consciousness . Hopefully, these preliminary results encourage continued, rigorous research — in the meantime, officials and the general public must remain vigilant.
 K. Thomas, D. Gelles, and C. Zimmer, “Pfizer’s Early Data Shows Vaccine Is More Than 90% Effective,” The New York Times, Updated November 12, 2020. [Online]. Available: https://www.nytimes.com/2020/11/09/health/covid-vaccine-pfizer.html.
 A. Park, “Pfizer Says COVID-19 Vaccine 90% Effective Against Virus,” Time, November 9, 2020. [Online]. Available: https://time.com/5909322/pfizer-covid-19-vaccine-effective/.
 The Economist, “The Promise of the New COVID-19 Vaccine is Immense,” November 14, 2020. [Online]. Available: https://www.economist.com/leaders/2020/11/14/the-promise-of-the-new-covid-19-vaccine-is-immense.
 The Economist, “An Effective COVID-19 Vaccine is a Turning Point in the Pandemic,” November 14, 2020. [Online]. Available: https://www.economist.com/briefing/2020/11/14/an-effective-covid-19-vaccine-is-a-turning-point-in-the-pandemic.
 J. Corum, S. Wee, and C. Zimmer, “Coronavirus Vaccine Tracker,” The New York Times, Updated November 11, 2020. [Online]. Available: https://www.nytimes.com/interactive/2020/science/coronavirus-vaccine-tracker.html.
 R. Robbins and D. Gelles, “How Pfizer Plans to Distribute Its Vaccine (It’s Complicated),” The New York Times, November 12, 2020. [Online]. Available: https://www.nytimes.com/2020/11/12/business/pfizer-covid-vaccine-coronavirus.html.