Pfizer-BioNTech COVID-19 Vaccine Trial Overview

Our Path to Developing an Investigational COVID-19 Vaccine

In the fight against COVID-19, a vaccine is a critical part of addressing the global health crisis by decreasing rates of infection, disease and death worldwide. Pfizer and BioNTech leveraged decades of scientific expertise to design and execute a rigorous Phase 3 clinical trial program to make our investigational COVID-19 vaccine available as quickly and safely as possible.

The landmark Phase 3 clinical trial began in late July 2020, recruiting participants aged 12 and over, and completed enrollment of 46,331 participants in January 2021. On December 11, 2020, the U.S. Food and Drug Administration (FDA) authorized the Pfizer-BioNTech COVID-19 vaccine for emergency use.

The Pfizer-BioNTech COVID-19 vaccine has not been approved or licensed by the U.S. Food and Drug Administration (FDA), but has been authorized for emergency use by FDA under an Emergency Use Authorization (EUA) to prevent Coronavirus Disease 2019 (COVID-19) for use in individuals 16 years of age and older. The emergency use of this product is only authorized for the duration of the declaration that circumstances exist justifying the authorization of emergency use of the medical product under Section 564(b)(1) of the FD&C Act unless the declaration is terminated or authorization revoked sooner. Please see EUA Fact Sheet at www.cvdvaccine.com.

Developing an investigational breakthrough vaccine to help prevent COVID-19 is only possible through the dedicated work of thousands of individuals and those who volunteer to take part in research. We are grateful to each of 153 clinical trial investigators and their study teams who are partnering with us in this effort and to all of the participants who volunteered to help make a difference for society. Participants 16 years and older that originally received the placebo have the option to receive the investigational vaccine while staying in the study through our Vaccine Transition Option. Vaccine doses for placebo recipients have been secured, and our aim is that that all participants 16 years and older who received the placebo will have the opportunity to receive their first dose of the investigational vaccine within the study by March 1, 2021, if they choose.

Trial Enrollment graphic

What's Next

In February 2021, we began a global Phase 2/3 study to evaluate the safety, tolerability, and immunogenicity of the Pfizer-BioNTech COVID-19 vaccine (BNT162b2) in preventing COVID-19 in healthy pregnant women 18 years of age and older. We plan to enroll approximately 4,000 healthy pregnant women in the U.S., Canada, Argentina, Brazil, Chile, Mozambique, South Africa, U.K., and Spain. After a participant’s infant is born, she will be unblinded and those who were in the placebo group will be given the opportunity to receive the vaccine. Additional information about the study can be found at www.clinicaltrials.gov under the identifier NCT04754594.

Pfizer and BioNTech also initiated an evaluation of the safety and immunogenicity of a third dose of the Pfizer-BioNTech COVID-19 vaccine (BNT162b2) to understand the effect of a booster on immunity against COVID-19 caused by the circulating and potential newly emerging SARS-CoV-2 variants. The study will draw upon participants from the Phase 1 study in the United States who will be offered the opportunity to receive a 30 µg booster of the current vaccine 6 to 12 months after receiving their initial two-dose regimen. The study is part of the Companies’ clinical development strategy to determine the effectiveness of a third dose including against evolving variants. To be prepared for any potential future strain changes, Pfizer and BioNTech are in ongoing discussions with regulatory authorities regarding a registration-enabling clinical study to evaluate a variant-specific vaccine having a modified mRNA sequence. This study would use a new construct of the Pfizer-BioNTech vaccine based on the B.1.351 lineage, first identified in South Africa. This could position the Companies to update the current vaccine quickly if the need arises to protect against COVID-19 from circulating strains. In keeping with the updated guidance issued by the FDA regarding emergency use of vaccines to prevent COVID-19 which provides recommendations for evaluating a modified vaccine to address variants, the Companies are hoping to pursue the validation of future modified mRNA vaccines with a regulatory pathway similar to what is currently in place for flu vaccines.

Pfizer and BioNTech expect to start additional studies in children between the ages of 5 and 11 over the next couple of months, and in children younger than 5 later in 2021. The Companies are also planning studies to further evaluate the vaccine in people with compromised immune systems.

Frequently Asked Questions

The Investigational Vaccine

What kind of vaccine is the investigational Pfizer-BioNTech COVID-19 vaccine?

The investigational Pfizer-BioNTech vaccine is an mRNA vaccine. It is a kind of vaccine that gives a body's cells instructions to make viral proteins that can be recognized by the immune system. It contains a small part of the genetic code for the SARS-CoV-2 spike protein. By delivering the mRNA to the body’s cells, the viral protein is expressed and an immune system response is generated against it, with the goal of preventing COVID-19 disease. The vaccine does not contain any live virus.

How are mRNA vaccines different than traditional vaccines?

There are many different types of vaccines used to help prevent infections, and all have the same goal: train your immune system to recognize and defend against organisms that cause disease by producing disease-fighting antibodies and activating immune cells, such as T-cells. Some conventional vaccines may be made up of weakened, dead, or noninfectious parts of a virus or bacterium. mRNA vaccines are different because they contain information about the infectious agent to give a body's cells instructions to make a viral protein that can be recognized by the immune system. 

The Clinical Trials

What was the objective of the Phase 1 portion of the clinical trial?

The Phase 1 clinical trial began in the U.S. and Germany in April 2020, and were designed to evaluate the safety, tolerability, and potential efficacy of up to four mRNA vaccine candidates and to select which vaccine candidate and dose should be taken forward for future clinical study. One vaccine candidate—BNT162b2 at a 30 µg dose level in a two vaccination course—was selected for the Phase 3 clinical trial and also received U.S. Food and Drug Administration Fast Track designation. Pfizer and BioNTech announced that data from the U.S. trial and German trial have been published and allowed for the program to continue.

The Phase 1 trial design was amended in February 2021 and Pfizer and BioNTech initiated an evaluation of the safety and immunogenicity of a third dose of the Pfizer-BioNTech COVID-19 vaccine (BNT162b2) to understand the effect of a booster on immunity against COVID-19 caused by the circulating and potential newly emerging SARS-CoV-2 variants.

What is the objective of the landmark Phase 3 clinical trial?

The Phase 3 clinical trial was designed to determine if the investigational BNT162b2 vaccine is safe and effective in preventing COVID-19 disease. This part of the trial began July 27, 2020, and completed enrollment of 46,331 participants in January 2021. On November 18, Pfizer and BioNTech announced that, after conducting the final efficacy analysis in their ongoing Phase 3 clinical trial, their mRNA-based COVID-19 vaccine candidate met all of the study’s primary efficacy endpoints. On December 10, 2020, Pfizer and BioNTech announced publication of results from this trial in the New England Journal of Medicine.

What were the endpoints in your Phase 3 landmark study?

The primary endpoints of the COVID-19 vaccine study were to evaluate the efficacy of the vaccine candidate in preventing COVID-19 disease in participants who had not been infected with the SARS-CoV-2 virus before they received the vaccine, and to evaluate potential prevention of COVID-19 disease in participants who had prior exposure to SARS-CoV-2.

The primary efficacy endpoints evaluated confirmed COVID-19 cases occurring 7 days or more after the second dose. The final analysis also included, with the approval of the FDA, secondary endpoints evaluating efficacy based on COVID-19 cases occurring 14 days after the second dose. Pfizer and BioNTech believe that the addition of these secondary endpoints enabled assessment of data across all COVID-19 vaccine studies and allowed for cross-trial learnings and comparisons between various vaccine platforms.

Pfizer also plans to continue to accumulate safety and long-term outcomes data from participants for a full two years.

Why was the landmark Phase 3 study randomized and placebo-controlled – why not give everyone the vaccine candidate?

There are many different types of clinical studies. Randomized, placebo-controlled studies are considered the “gold standard” in clinical research, because they eliminate potential biases when interpreting data.

One reason we chose this type of study to test our vaccine candidate was that it helped us understand whether people who received the vaccine candidate were better protected from COVID-19 disease than people who do not receive it.

Now that the study has completed, we are in the process of giving all placebo participants the option to receive the vaccine.

Who participated or was able to participate in the landmark Phase 3 study?

We enrolled 46,331 people in the trial, with the majority of participants ranging from ages 18-56. Additional trial populations included people as young as 12 years old and people with chronic, stable HIV (human immunodeficiency virus), HCV (Hepatitis C virus), or HBV (Hepatitis B virus) infections. We believe that doing so enabled more individuals who were at risk of COVID-19 disease to have the opportunity to participate in the study. As with the vaccine candidates we test in adult populations, we followed a careful, stepwise approach as we moved down to younger age groups.

How were you able to move with speed in the landmark Phase 3 trial?

Even though we moved with extraordinary speed, preservation of high quality and safety standards was critically important throughout development. We took all of the regulatory and operational steps that we would normally take for all of our vaccine trials, maintaining the highest standards in our development process. This required enormous mobilization of Pfizer and BioNTech resources upfront at a scale never seen before. We also worked closely with regulatory agencies, providing near real-time data and receiving review and advice more quickly than ever before, to support the development of this potential vaccine as quickly as possible.

What are the objectives of the booster dose study with participants from the Phase 1 trial?

The study will evaluate the safety and immunogenicity of a third dose of the Pfizer-BioNTech COVID-19 vaccine (BNT162b2) to understand the effect of a booster on immunity against COVID-19 caused by the circulating and potential newly emerging SARS-CoV-2 variants.

Who will be participating in the initial booster trial? How many people are you planning to enroll?

The study will draw upon participants from the Phase 1 study in the United States who will be offered the opportunity to receive a 30 µg booster of the current vaccine 6 to 12 months after receiving their initial two-dose regimen.

What are the objectives of the Phase 2/3 study in pregnant women?

The Phase 2/3 clinical trial will evaluate the safety and immune response in healthy pregnant women 18 years of older between 24-34 weeks of their pregnancy. We plan to enroll approximately 4,000 participants at more than 130 global sites within the U.S. Canada, Argentina, Brazil, Chile, Mozambique, South Africa, U.K. and Spain. Each woman will participate in the study for approximately 7 to 10 months, depending on whether she was randomized to receive the vaccine or placebo.

Why is it important to conduct a separate study in pregnant women?

We need to continue to gather the evidence on safety and efficacy to potentially support the use of the vaccine by important subpopulations. In general, pregnant women are considered a vulnerable population given the unique changes that happen to their bodies during pregnancy. The safety of vaccines during pregnancy, however, is well documented and supported from multiple randomized clinical trials and observational studies that have demonstrated vaccines such as tetanus, Tdap, and Influenza to be safe for use during pregnancy.

Commitment to Safety

How are you monitoring the safety of trial participants?

Participant safety is paramount. As with all of our trials, we are following all of the rules and regulations in place to ensure participant safety. For example, the trial protocols are reviewed by regulatory authorities and approved by ethics committees or Institutional Review Boards, which are independent committees that review the methods proposed for research. In addition, the trial’s progress is closely monitored by both Pfizer and an outside group of independent experts called a Data Monitoring Committee or DMC. Trial investigators are also responsible for monitoring participants health, and participants in the trial have regular planned follow-up visits as part of the trial.

Will long-term safety and effectiveness be tracked beyond the trial?

We will monitor participants’ health for two years after they receive their second dose of the vaccine. Pfizer will continue to perform safety surveillance after potential licensure of a COVID-19 vaccine, if that occurs, and government authorities, such as the Centers for Disease and Control (CDC), will also conduct safety surveillance.

We have also funded a study, conducted by The Duke Clinical Research Institute (DCRI) and Verily, utilizing the HERO Registry and community to gain long-term insights about the investigational Pfizer-BioNTech COVID-19 vaccine, including real-world safety data. This safety study, HERO-Together, will enroll approximately 20,000 healthcare workers after they receive the vaccine and will follow them for two years, inviting participants to provide information about their health and any unexpected medical care they have received.

Commitment to Diversity

COVID-19 has disproportionately affected underrepresented populations. How are you addressing this in the trial?

We are committed to decreasing health disparities in underrepresented populations through our clinical trials. We selected investigative sites in diverse communities in the U.S. and globally that were disproportionately affected by COVID-19, to help ensure that individuals in communities that have been most impacted had the opportunity to participate. In our landmark phase 3 study, approximately 42% of overall and 30% of U.S. participants came from diverse backgrounds. We shared with our investigative sites the importance of recruiting individuals who fully represent the racial and ethnic diversity of their communities, and we engaged patient advocacy partners and community groups to raise awareness about the importance of participation and representation.

Development Milestones

February 25, 2021

Pfizer and BioNTech Initiate a Study as Part of Broad Development Plan to Evaluate COVID-19 Booster and New Vaccine Variants

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December 21, 2020 - 2 PM

Pfizer and BioNTech Receive Authorization in the European Union for COVID-19 Vaccine

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December 21, 2020 - 9 AM

Pfizer and BioNTech Receive CHMP Positive Opinion for their COVID-19 Vaccine

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December 11, 2020

Pfizer and BioNTech Celebrate Historic First Authorization in the U.S. of Vaccine to Prevent COVID-19

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December 10, 2020

Pfizer and BioNTech Announce Publication of Results from Landmark Phase 3 Trial of BNT162b2 COVID-19 Vaccine Candidate in The New England Journal of Medicine

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December 2, 2020

Pfizer and BioNTech Achieve First Authorization in the World for a Vaccine to Combat COVID-19

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November 20, 2020

Pfizer and BioNTech to Submit Emergency Use Authorization Request Today to the U.S. FDA for COVID-19 Vaccine

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November 18, 2020

Pfizer and BioNTech Conclude Phase 3 Study of COVID-19 Vaccine Candidate, Meeting All Primary and Secondary Efficacy Endpoints

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November 9, 2020

Pfizer and BioNTech Announce Vaccine Candidate Against COVID-19 Achieved Success in First Interim Analysis from Phase 3 Study

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September 15, 2020

Pipeline Advances and COVID-19 Vaccine Candidate Updates

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September 12, 2020

Proposal to Expand Clinical Trial Announced

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September 9, 2020

Data from Preclinical Studies of Vaccine Candidate

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September 8, 2020

Biopharma Leaders Unite to Stand with Science

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August 20, 2020

Positive Early Data from Phase 1/2 Study of Lead Vaccine Candidate Announced

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August 12, 2020

Peer-Reviewed Phase 1/2 Data Published Online in the Journal Nature

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July 27, 2020

Lead Covid-19 Vaccine Candidate Selected and Global Phase 2/3 Clinical Study Begins

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July 20, 2020

Early Positive Data from Ongoing Phase 1/2 Clinical Trial in Germany Announced

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July 13, 2020

Pfizer and BioNTech Granted Fast Track Designation

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July 1, 2020

Early Positive Data from Ongoing Phase 1/2 Clinical Trial in the U.S. Announced

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May 5, 2020

Pfizer and BioNTech Dose First Participants in the U.S.

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April 29, 2020

Testing of Vaccine Candidates in Humans Begins in Germany

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April 22, 2020

Regulatory Approval from German Authority to Begin Trial

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April 9, 2020

Pfizer and BioNTech Announce Further Details on Collaboration

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March 17, 2020

Pfizer and BioNTech Announce Plans to Co-Develop a Potential COVID-19 Vaccine

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March 13, 2020

Pfizer CEO Albert Bourla States 5-Point Plan to Battle COVID-19

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March 11, 2020

The World Health Organization (WHO) Declares the COVID-19 Outbreak a Global Pandemic

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August 16, 2018

Pfizer and BioNTech Establish Partnership to Develop mRNA Vaccines

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Learn more about progress on our path to develop a COVID-19 vaccine.

 

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