Coronavirus Scientific Resources

Resources to educate and collaborate on COVID-19 responses

In confronting this crisis, we believe that science will win. Be sure to keep up with all of our important updates surrounding COVID-19, including press releases, supply updates and more.

COVID-19 Featured Publication

Featured Coronavirus Publication

A Phase 1/2/3 Study to Evaluate the Safety, Tolerability, Immunogenicity, and Efficacy of RNA Vaccine Candidates Against COVID-19 in Healthy Individuals

A Phase 1/2/3, Placebo-Controlled, Randomized, Observer-Blind, Dose-Finding Study to Evaluate the Safety, Tolerability, Immunogenicity, and Efficacy of SARS-COV-2 RNA Vaccine Candidates Against COVID-19 in Healthy Individuals

Read the protocol

How Pfizer's COVID-19 Clinical Trial Is Designed

Pfizer has a deep heritage in vaccine development. Our team of in-house experts has decades of experience developing vaccines and study protocols (a document that outlines the objectives, design, and methodology for a clinical trial), to potentially help prevent serious, emerging, and life-threatening infections and diseases.

We have made the protocol for our COVID-19 vaccine study available to reinforce our longstanding commitment to scientific and regulatory rigor that benefits patients. Learn more about the protocol and our study below.

Frequently Asked Questions

Trial Design

What is the goal of the Pfizer and BioNTech COVID-19 vaccine study?

The Phase 2/3 part of our study is designed to determine if Pfizer and BioNTech’s vaccine candidate, called BNT162b2, is safe and effective in preventing COVID-19 disease, when compared to placebo.

How will you determine if the study met its goal?

To determine if our vaccine candidate is safe and effective in preventing COVID-19, our study protocol specifies primary and secondary endpoints: the events or outcomes used to objectively measure potential success or failure. Endpoints are set at the beginning of the trial and agreed with FDA before recruitment commences. The study’s safety and efficacy endpoints are reviewed independently by an external Data Monitoring Committee (DMC) to ensure objectivity and scientific rigor.

What are the endpoints in your study?

  • The primary endpoints of our COVID-19 vaccine study are to evaluate the effectiveness of the vaccine candidate in preventing COVID-19 in participants who have not been infected with the SARS-CoV-2 virus before they receive the vaccine, and to evaluate potential prevention of COVID-19 disease in participants who have had prior exposure to SARS-CoV-2.
  • The secondary endpoints in our study include evaluation of the investigational vaccine in the prevention of severe COVID-19, and the potential for the vaccine candidate to provide long-term protection against COVID-19 disease, whether or not study participants have had prior infection with the SARS-CoV-2 virus.
  • Pfizer also plans to continue to accumulate safety and long-term outcomes data from participants for a full two years.

How is the study designed and reviewed over time?

  • The study is designed to take place in multiple locations (multi-center), in different countries (multi-national), and participants will have a 50% chance of receiving either the vaccine candidate or a placebo (randomized, placebo-controlled).
  • The study is also “observer-blinded,” which means that trial participants and investigators do not see the vial that contains the vaccine candidate or placebo. This accounts for any visual differences that may exist between the vaccine candidate and placebo and adds to the rigor of the study.
  • Participants are given two doses of the vaccine candidate or placebo, 21 days apart. Participants will continue to be monitored for long-term protection and safety for an additional two years after the second dose.
  • The study is a case count, or “event-driven,” study: investigators count the number of cases of COVID-19 that occur in those who receive the vaccine candidate and those who receive the placebo. If there are many more COVID-19 cases in the placebo group, compared to the vaccine group, this is scientific evidence that our vaccine candidate is effective in preventing COVID-19.

Why is the 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 often 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 is that it will help us understand whether people who receive the vaccine candidate are better protected from COVID-19 than people who do not receive it.

When will you review data from the study?

  • Given the urgency of the public health threat presented by COVID-19, we designed our study in a way that allows the data to be reviewed by an independent, external Data Monitoring Committee (DMC) regularly, including at four pre-specified time points, called interim analyses. This will enable researchers to understand how the vaccine candidate is performing in the study, prior to the full final efficacy analysis.
  • Our interim analyses will focus on the primary efficacy endpoint, which is to assess whether the vaccine is effective in protecting against COVID-19.
  • Given the current infection rates, we anticipate that these interim analyses could happen within weeks of each other, and we will continue to collect data on safety and efficacy thereafter.

Who is participating or able to participate in the study?

  • We expanded our initial, planned enrollment in the study from 30,000 people to approximately 44,000 people. This allowed us to include additional populations, including people as young as 16 years and people with chronic, stable HIV (human immunodeficiency virus), HCV (Hepatitis C virus), or HBV (Hepatitis B virus) infections. We believe that doing so will enable more individuals who are also at risk of COVID-19 to have the opportunity to participate in the study.
  • We have also received permission from the FDA to seek institutional review boards (IRB) or ethics committee approval of an amendment to our protocol, which will enable us to study adolescents as young as 12 years old. As with the vaccine candidates we test in adult populations, we are following a careful, stepwise approach as we move down to younger age groups.
  • To ensure the study provides substantial data, participants in the study must fit certain standards, called “inclusion criteria.” Inclusion criteria for this study are:
    • Healthy males or females over the age of 16 (age 12 or over with IRB or ethics committee approval)
    • Willing and able to comply with all scheduled visits, laboratory tests, lifestyle restrictions and other study procedures
    • In the judgment of the investigator, higher than average risk for COVID-19 infection (including, but not limited to, use of mass transportation, relevant demographics, and frontline essential workers)
  • The earlier we can understand the safety and efficacy of our vaccine candidate in our current study population, the sooner we can work with the FDA and others to potentially study the vaccine candidate in other populations, including pregnant women.

Maintaining Safety & Integrity

What mechanisms are in place to ensure the integrity of the trial?

  • Before our trial began, the protocol was reviewed and approved by the U.S. Food and Drug Administration (FDA), regulatory authorities in the countries where the trial is taking place and institutional review boards (IRBs) or ethics committees.
  • Throughout the trial, progress is closely tracked by an outside group of independent experts, called a Data Monitoring Committee (DMC), which also monitors our study for safety on an ongoing basis.

What is an Institutional Review Board (IRB)?

  • Under FDA regulations, an IRB is an appropriately constituted group that has been formally designated to review and monitor biomedical research involving humans. In accordance with FDA regulations, an IRB has the authority to approve, require modifications in (to secure approval), or disapprove research. This group review serves an important role in the protection of the rights and welfare of research participants.
  • The purpose of IRB review is to assure, both in advance and by periodic review, that appropriate steps are taken to protect the rights and welfare of people participating in the research. To accomplish this purpose, IRBs use a group process to review research protocols and related materials (e.g., informed consent documents and investigator brochures) to ensure protection of the rights and welfare of participants.

What is the Data Monitoring Committee (DMC) and how is it structured?

The DMC for our COVID-19 vaccine trial currently consists of a chairperson and four additional members. The members are experts with extensive experience in pediatric or adult infectious diseases, vaccine safety and statistics. All DMC members have prior experience as members on DMCs.

How are you keeping study participants safe, and making sure the trial is conducted in a fair, open and ethical way?

Participant safety is our number one priority. As with all our trials, we are following strict rules and regulations to protect the safety of the participants. The trial’s progress is closely monitored by both Pfizer and an independent external Data Monitoring Committee (DMC). Trial investigators are also responsible for monitoring participants’ health, and participants have regular planned follow-up visits as part of the trial.

What is a “serious adverse event” and what will happen if a trial participant reports one?

  • A serious adverse event (SAE) in this trial, and in all standard clinical protocols, is defined as any untoward medical occurrence that causes death, is life-threatening, requires hospitalization, or results in disability, whether or not the occurrence is connected to the investigational vaccine being studied.
  • Serious Adverse Events Following Immunization (AEFI) in the clinical trial are analyzed to understand if they could be causally related to the trial intervention, and follow-up actions are taken as appropriate.
  • AEFIs are reported to regulatory agencies, as well as to an outside group of independent experts called the Data Monitoring Committee (DMC), which has access to unblinded data. 

Next Steps & Timing

When will you know if the study met its goal or if the vaccine candidate works?

  • In vaccine development, clinical trials like this are called efficacy trials and are “event-driven” to help us understand if the vaccine candidate works or is effective. This is accomplished by comparing the number of COVID-19 cases in the vaccine group versus those in the placebo group to determine whether the vaccine is protective.
  • In this study, we expect to reach a total of 164 cases of COVID-19 that occur at least seven days following the last injection among the ~44,000 people participating in the trial, spread between the vaccine candidate and placebo groups.
  • During the interim analyses, the data will be reviewed by an independent external Data Monitoring Committee (DMC). If the data is strong, which would mean showing clear evidence of efficacy in participants who have received the vaccine candidate versus those who received the placebo, and an acceptable risk/benefit profile has been adequately established, the DMC may declare that efficacy has been demonstrated.

If it’s determined that the vaccine candidate works, what are the next steps?

  • If the study is successful in demonstrating that the vaccine candidate has a satisfactory safety profile and helps to prevent COVID-19, Pfizer and BioNTech plan to apply for authorization or regulatory approval with the FDA and other regulatory bodies. We are committed to providing efficacy and safety data to help the FDA and other regulatory agencies determine the best way to make the potential vaccine available to the public.
  • Pfizer also plans to continue to accumulate safety and long-term outcomes data from participants for a full two years.

Could the study be ended early, and if so, under what circumstances? Why?

  • The study is designed so that even if efficacy of the potential vaccine is demonstrated at any interim analysis, the trial would not stop right away. Pursuant to our protocol, we currently plan to follow participants for 2 years following the second dose. In that event, we would continue conversations with our external independent Data Monitoring Committee (DMC) and regulators, including the FDA, to request guidance and determine appropriate next steps for the study protocol and participants.
  • The trial could be halted by the DMC if the vaccine candidate is proven extremely effective or is ineffective or unsafe.
  • Regardless of whether we have a successful data readout at one of the interim analyses, the trial will continue to follow participants for 2 years to determine long-term safety and efficacy.

How will study participants be followed during 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 candidate or placebo. 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), would also conduct safety surveillance.


Antiviral Efforts -
Advancing our protease inhibitors:

Vaccine Efforts -
Potentially preventing infections using mRNA vaccines:

Anti-infective Efforts -
Sharing azithromycin data:

In an effort to share information that could benefit COVID-19 mitigation efforts, Pfizer researchers published a review in Clinical Pharmacology and Therapeutics which assesses published in vitro and clinical data regarding azithromycin as an agent with antiviral properties. This open access review may serve to facilitate the use of azithromycin in future research on COVID-19. Azithromycin is not approved for the treatment of viral infections.

Research that may inform future vaccination guidelines

Pfizer Inc. and the Liverpool School of Tropical Medicine’s Respiratory Infection Clinical Research Group launched two new studies to provide insights on the interaction between S. pneumoniae and SARS-CoV-2. Pfizer's collaboration agreement with Liverpool provides funding and in-kind laboratory testing support for this research.

Collaborating to address COVID-19

As outlined in Pfizer’s five-point plan, the company has been collaborating across the healthcare innovation ecosystem ranging from large pharmaceutical companies to the smallest of biotech companies, from government agencies to academic institutions to address the COVID-19 global health care crisis.

If you’re a researcher interested in collaborating, contact Robert.Bagdorf[email protected]

Existing collaborations:


For additional information about Pfizer, please see our filings with the U.S. Securities and Exchange Commission, including the information provided in the sections captioned “Risk Factors” and “Forward-Looking Information and Factors That May Affect Future Results”.