Should You Join a Vaccine Clinical Trial? A Guide for Potential Volunteers

Should You Join a Vaccine Clinical Trial? A Guide for Potential Volunteers

Clinical trial volunteers play a crucial role in advancing medical research. Taking part in a vaccine trial helps researchers develop safe and effective vaccines that protect our health and help prevent the spread of diseases. Your involvement can contribute to critical breakthroughs that may benefit communities worldwide.

There are many reasons why people choose to take part or not take part in vaccine clinical trials. Before deciding whether participation in a vaccine trial is right for you, there are certain things you should consider. Understanding what’s involved in the trial process is key to making the right choice. In this article, we’ll explore all these points to help you feel more informed and confident about your decision.

How are new vaccines developed?

Should You Join a Vaccine Clinical Trial? A Guide for Potential Volunteers - Vaccine Clinical Trial,Clinical Trial Volunteers,Research Participants,Research Volunteers,Clinical Research

Basic research

Vaccine development begins in the laboratory and often takes around 10 – 15 years of basic research. This involves identifying and isolating the viral or bacterial factor that triggers an immune response, copying the genetic material, and developing a vaccine delivery method.

Preclinical testing

Once created, the new vaccine is tested in small animals to show that it causes an immune response. This is called preclinical testing. Adjustments are made to improve its effects and address any early safety issues before testing in humans.

Clinical trials

Before a new vaccine is approved for use in humans, it must pass a series of clinical studies to show that it is safe and effective. The approval process involves three phases of clinical trials:

phase I clinical trials
20 - 100 healthy volunteers.

To study the vaccine’s safety, identify side effects, and see if it causes an immune response.

phase II clinical trials
100 – 300 participants, including people at risk of infection/disease.

To confirm that the vaccine is safe (with only minor side effects) and study how well it causes an immune response.

phase III clinical trials
100 – 300 participants, including people at risk of infection/disease.

To test how effective the vaccine is at preventing infection/disease, compared to people who don’t receive the vaccine. During this phase, the vaccine is usually compared to a placebo (a ‘fake’ vaccine).

Once a vaccine has been approved for use, further evaluation and safety data collection continue with Phase IV trials.

(For a detailed overview of clinical trials, read our Introduction to Clinical Trials blog.)

What does participation in a vaccine clinical trial involve?

Every clinical trial journey will look different depending on the clinical trial phase and study plan. A typical vaccine trial journey is summarised below.

Screening visit

Screening is a process to determine if you qualify to join a trial. This visit is often combined with the baseline visit (below). You will meet with the study coordinator and doctor to discuss the trial. You will receive a copy of the participant information sheet and consent form (PICF), which tells you all you need to know about taking part in the study. The doctor will confirm that you understand this information and answer any questions. You may then sign the informed consent form. The doctor will then assess your eligibility to join the trial against certain inclusion and exclusion criteria. Screening normally includes a review of your medical history and medications, physical examination, measuring your vital signs, and a pregnancy test.

Baseline visit

If you are eligible to participate, more measurements or tests may be conducted to complete your baseline (before vaccine) data collection. If the trial involves two participant groups, for example, a placebo-controlled trial, you will be randomly assigned to one of the groups to receive either vaccine or placebo. You will not know which treatment you receive.


The vaccine (or placebo) will be given at the end of the baseline visit. After receiving the injection, you must stay at the study site for a specified amount of time to be monitored for any possible side effects.

Health diary

Most vaccine trials involve the use of an ‘e-diary’ (an app downloaded onto your phone) to regularly track your health and any side effects during the trial. The study staff will teach you how to use the e-diary during your baseline visit.

Follow-up visits

The number and timing of follow-up visits will depend on the study plan. These visits typically involve a review of your health and medications, assessment of any side effects, blood tests to see how your immune system is reacting, and tests to check for disease/infection. Extra visits may be needed if you experience any severe side effects.

(For more information about what happens after a clinical trial, read this blog.)

How safe are vaccine clinical trials?

Regulation and ethics

Clinical trials are heavily regulated and must be conducted in accordance with ethical standards, guidelines, and national laws.

Before testing in people, the pharmaceutical company must submit an application to the regulatory authority to use the unapproved vaccine in a clinical trial. In Australia, this is the Therapeutic Goods Administration (TGA). The application process involves reviewing preclinical data, manufacturing, risk management, and other important information.

In addition, the clinical trial plan must be reviewed and approved by a human research ethics committee to confirm that it meets ethical standards and guidelines. This aims to ensure protection of the rights, welfare, and wellbeing of research participants, and that the benefits of the study greatly outweigh the possible risks. Once approved, the clinical trial may begin.

The ethics committee continues to review the trial’s progress and safety reports. If there are any serious safety issues, the trial may be stopped.

Participant safety

The study team are highly dedicated to protecting your health and safety. A typical team includes doctors, research coordinators, nurses, pharmacists, and research support staff. All are trained in the ethical conduct of clinical trials.

Any side effects that occur during the trial will be documented and followed-up by the study doctor until they have settled. You should contact the study team if you experience any side effects or have concerns. They can arrange for you to see the study doctor and answer any questions.

Why do people volunteer for vaccine clinical trials?


The act of “doing something for the greater good” motivates many people to join trials. They recognise the importance of participation for the advancement of vaccines, community health, and the safety of others.

A sense of responsibility

In a review article, it was reported that healthcare professionals often participate because they feel a sense of obligation or duty to contribute to medical research. Some said they wanted to set a good example for their patients and volunteers, and to demonstrate that vaccines are safe.

Potential health benefits

The chance to gain protection against disease motivates many people. This is especially true for those who are considered ‘high risk’, or who work in high-risk environments. In addition, many people see volunteering as a way to protect their family members and other vulnerable people in their lives.

Quality healthcare

Clinical trial participants have access to dedicated support and resources throughout the trial. This includes high quality medical care and personnel dedicated to answering any questions or concerns related to the study.

Take home message

Clinical trial volunteers play a vital role in advancing vaccines and safeguarding community health. The decision to participate is both important and personal. Before you decide to take part in a clinical trial, remember that:

§  Your participation is entirely voluntary. You have the right to withdraw from a trial at any time.

§  Clinical trials are conducted under strict regulatory and ethical guidelines to protect your rights, welfare, and wellbeing.

§  All clinical trials come with potential benefits and risks. Read the study information provided to you carefully and ask any questions you may have.

To learn more about clinical trial participation, visit our Participant Information page.

If you are interested in participating in a clinical trial, visit our Join a Trial page to view our currently enrolling clinical trials or register your interest for future studies.

References and resources:

  1. Centers for Disease Control and Prevention. “How Vaccines are Developed and Approved for Use”. S. Department of Health and Human Services. Reviewed 20 March 2023.
  2. Dean A, Rose F, Jones K, Scantlebury A, Adamson J, Knapp P. “Why do people take part in vaccine trials? A mixed methods narrative synthesis”. Patient Educ Couns. 2023; 114: 107861.
  3. Ekezie W, Vaz LR, Czyznikowska B, Akroyd C, Davies M, Khunti K. “Understanding the factors associated with willingness to participate in a COVID-19 vaccine clinical trial”. The National Institute for Health Research. Applied Research Collaboration East Midlands. December 2020. Available via:
  4. National Institutes of Health (NIH): COVID-19 Research. “The Journey of a Vaccine”. S. Department of Health and Human Services.
  5. Therapeutic Goods Administration. “Good Clinical Practice (GCP) for clinical trials in Australia”. Australian Government Department of Health and Aged Care. Updated 25 October 2023.
  6. Therapeutic Goods Administration. “How COVID-19 vaccines are tested and approved”. Australian Government Department of Health and Aged Care. Updated 14 August 2023.
  7. Therapeutic Goods Administration. “Vaccine safety”. Australian Government Department of Health and Aged Care. Updated 7 August 2023.
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