Frequently asked questions

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What are clinical trials?

Clinical trials (or research studies) are a type of medical research in which people volunteer to take part. Clinical trials commonly study how potential medicines and other medical treatments affect the participants.

Every medicine and vaccine that becomes available today is first tested in clinical trials. These trials — and the breakthroughs that result from them — would not be possible without volunteers.

What happens in a clinical trial?

What happens in a clinical trial depends on the ‘protocol.’ A protocol is a detailed plan that explains the purpose of the clinical trial and how it will be run. If you consider joining a clinical trial, these details will be explained to you as part of the informed consent process. They include:

  • the length of the clinical trial
  • the study medicines, procedures, and tests in the clinical trial
  • the schedule of study activities
  • information about who can participate
  • how side effects will be tracked, managed, and reported
  • the rules that must be followed

For more information about how clinical trials work, click “Learn more” to visit

Who can participate in a clinical trial?

Anybody can consider participating in clinical research.

When you join a clinical trial that’s studying a condition you have, you may help us evaluate a potential treatment for that condition.

There are also clinical trials that need volunteers without a specific disease or condition. As a participant, you might contribute to learnings about a potential vaccine, or about a study medicine before it’s given to people with a condition.

Each clinical trial has its own criteria for who may participate. These are called eligibility criteria. Examples of eligibility criteria include a person’s:

  • Age and sex
  • Type and/or stage of disease
  • Overall health
  • Personal treatment history

Participation in a clinical trial is always voluntary. The decision to join is personal, and it is yours. (You can still take part in PfizerLink, even if you choose not to participate in a Pfizer clinical trial.)

Who will oversee my care in a clinical trial? Can I continue to see my regular medical doctor?

As part of a clinical trial, your study-related medical care is provided by the study team at the location where you’re participating. This includes the principal investigator (or study doctor) — the healthcare professional who conducts and takes responsibility for the trial at that location — as well as other clinical study team members.

During your clinical trial, you may also continue to see your regular medical doctors for any care that is not related to the study. It is important for you to tell your study team about other conditions you might have, and to let them know which other doctors are caring for you. This helps the study team coordinate your overall care.

If you participate, the clinical trial will provide study-related medical care, and your regular medical doctors will address the other aspects of your health. Your regular medical doctors can also work with the study team to understand the details of the study and any impact it may have on your regular medical care.

Are clinical trials safe?

All clinical trials have possible risks. The known and unknown risks of participating in a specific study will be explained to you during the informed consent process that happens before you decide whether to participate.

Clinical researchers must follow guidelines and regulatory requirements to help protect the rights, safety, and well-being of clinical trial participants. These include Good Clinical Practice (GCP). GCP is an international ethical and scientific quality standard for designing and conducting clinical trials.

There are also many entities that provide oversight of clinical trials. These include the U.S. Food & Drug Administration, institutional review boards and independent ethics committees, and data and safety monitoring boards.

For more information about protections for clinical trial participants, click “Learn more” to visit

Is there any cost to participate in a Pfizer clinical trial?

Pfizer generally covers the cost of the study medicines and procedures that are part of our clinical trials.

Pfizer is also committed to reimbursing participants for reasonable clinical trial-related expenses such as transportation, parking, and meals.

Because each study is different, we encourage you to ask the study team any questions you have. You can also refer to the informed consent document for the details about any costs for study participants and study-related reimbursement.

Will I be compensated for participating in a Pfizer clinical trial, beyond reimbursement for expenses?

The answer to this question depends on the specific clinical trial. Pfizer offers reasonable compensation for the time and effort of participating in our clinical trials.

In certain studies, reasonable compensation may be provided to parents, guardians, or caregivers.

You can refer to the informed consent document for the details about compensation for participation in a specific study.