What are Clinical Trials Hero Background

What Are
Clinical Trials

Clinical trials are carefully controlled scientific studies that evaluate how well new or modified medicines may treat or prevent diseases in people.

Clinical trials are conducted to answer questions such as:

Is the investigational treatment or vaccine safe enough to outweigh the risks?

A clinical trial follows a protocol that has been approved by the FDA and other regulatory agencies in order to ensure patients’ and trial volunteers’ safety. The protocol outlines the types of trial participants to include, the schedule of study visits and procedures, safety precautions, and what and how study data will be analyzed.

What Are the
Phases of Clinical Trials?

All new treatments and vaccines must go through several stages of research (also called “phases”) in order to determine if the new treatment or vaccine is safe and effective in people. Clinical trials are usually conducted in four phases that build on one another, with each phase designed to answer certain questions.


Before testing in people, investigational treatments undergo laboratory and animal testing to answer basic questions about safety.

Who Is Involved
in a Clinical Trial?

Frequently Asked Questions
About Clinical Trials

What are the main types of clinical trials?

The two main types of clinical trials are interventional and observational. Interventional trials are designed to find out if a an interventional medicine intended to treat or prevent a disease or illness is safe and effective. Observational studies collect data on a group of people who are not given any treatment specific to the trial outside of their routine medical care.

What is blinding?

Blinding is when the participants in a clinical trial do not know whether they received the investigational treatment or vaccine, or a placebo. This prevents bias from influencing the clinical trial results. There are two main types of blinded trials:

  • Single-blind: the participants do not know what treatment they received, but the study team is informed.

  • Double-blind: neither the participants nor the study team know what treatment has been given.

What is a placebo?

In order to better know if the investigational treatment or vaccine works, researchers may compare the investigational treatment or vaccine to an inactive drug called a placebo, which can be a sugar pill or saltwater solution. A placebo looks like the investigational treatment or vaccine being tested but does not contain an active ingredient.

All participants receive the same level of quality care regardless of whether they are assigned to the investigational treatment or vaccine, or the placebo.

What is a healthy volunteer?

A healthy volunteer is a clinical trial participant with no major health problems. They are needed in early phase clinical trials to determine if the investigational treatment or vaccine is safe and tolerable, or to compare to a group of patients with a disease being studied. Clinical trial participants can include healthy volunteers and patient volunteers with the disease under study.

Healthy volunteers play a vital role in clinical research and are essential throughout all phases of vaccine clinical trials.

Are clinical trials safe?

Researchers are required by law to follow strict regulations and policies to help protect the privacy, health, safety, and well-being of people who take part in clinical trials. All clinical trial participants are closely monitored by study doctors. The Institutional Review Board (IRB) also is dedicated to ensuring that the potential risks to clinical trial participants are as low as possible.

What are adverse events?

Adverse events are unexpected and/or harmful effects that occur during treatment with a drug or therapy. They may be mild, moderate, or severe. A study doctor closely follows participants for any adverse effect. It is important for clinical trial participants to report any adverse effects to the study team throughout their participation.

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