How Do COVID-19 Clinical Trials Work With Kids?

Clinical Trials in Kids

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Key Takeaways

  • Clinical trials are proven safe in adults or animals before kids will be included.
  • Children must also agree to be involved in a trial.
  • Children are not just mini-adults, so clinical trials in children are important for showing safety and effectiveness of a treatment.

Clinical trials are nothing new, nor are clinical trials in children. But, with the recent approval and initial distribution of COVID-19 vaccines, and further trials now approved for children aged 12 to 17 years, many parents are wondering how clinical trials work, if their children should be involved, and what a timeline might look like for having their kids vaccinated.

Here, we break down for you how vaccine clinical trials are structured, the role children play in trials, issues of consent, the ethics of testing on children, and what parents may like to consider before enrolling their children in a study.

Structure of Vaccine Clinical Trials

Typically, vaccine clinical trials are conducted in four phases. Often this testing compares the vaccine itself against a placebo, such as a saline injection. The participants, caregivers, and most researchers do not know who is given the real vaccine versus the placebo during the testing.

  • Pre-clinical phase: Tests in a laboratory, typically on animals like mice.
  • Phase 1: Tests on a small number of healthy participants to assess safety.
  • Phase 2: Tests on hundreds of people to assess safety and immunogenicity (the ability of the substance to provoke an immune response).
  • Phase 3: Tests on thousands of people to assess safety and immunogenicity.
  • Post-clinical phase: Assessments continue after the vaccine has been released and licensed to constantly monitor safety and efficacy.

These phases are usually conducted one after the other over a number of years. However, the urgency of developing a COVID-19 vaccine means that clinical trials are going through combined-phase trials. So when data is becoming evident in phase two, phase three commences simultaneously. This speeds up the availability of results and data.

Sharon Nachman, MD, chief of the division of pediatric infectious diseases at Stony Brook Children's Hospital helps explain these combined-phase trials. She says, “They started the phase two [trials] which really was going to look at immunogenicity. And when a certain number of immunogenicity targets were hit, then they opened up a phase three study to see if it was effective or not.”

She also reassures parents that because we already know what level of an immune response (immunogenicity) is needed in the body to create immunity to COVID-19, these combined phase trials may not be necessary for pediatric clinical trials. Rather, we may just need to test the dosage to find out how much of the vaccine children need to achieve the same level of an immune response.

While trials are still ongoing, it should be a matter of months—not years—before children can safely be vaccinated against COVID-19 infection.

Children in Clinical Trials

To protect children from potential harm, they are not included in the initial phases of trials that are relevant population-wide. However, it is important that children are eventually included in testing.

A child’s body does not metabolize and process all medicines the same as adults. Therefore, if testing is not conducted in children and we instead simply alter the doses of adult medicines based solely on body weight, the outcomes can potentially be harmful or not effective at all.

Sharon Nachman, MD, PhD

It's mathematically driven... It's not guesswork.

— Sharon Nachman, MD, PhD

Nachman reassures parents that sophisticated mathematical models are used to calculate potential effective doses in children. She says, “It's mathematically driven... It's not guesswork.” Despite this, the final precision of an effective and safe dose can only be determined by clinical trials in children.

Amina Ahmed, MD, professor of pediatric infectious disease and immunology at Atrium Health Levine Children's Hospital, adds that testing in children generally won’t occur until safety is proven in adults.

Amina Ahmed, MD

Normally it would be sort of a graded response. You [test] down to sixteen, and then down to twelve, and down to age two, and then infants.

— Amina Ahmed, MD

Once proven in adults, teens are often the next group tested. Ahmed explains “normally it would be sort of a graded response. You [test] down to sixteen, and then down to twelve, and down to age two, and then infants.” Data is generally collected and evaluated before any testing commences in the younger groups.

Consent in Children

According to the World Health Organization (WHO), legal consent is required by the child’s legal guardian. However, children must also be given information about their participation in age-appropriate language.

Children involved in clinical trials should be allowed to ask any questions and should provide assent (agreeance to the procedure) prior to being involved. According to the Ethical Considerations for Clinical Trials in Children document published by the WHO, assent should be obtained repeatedly with each dose and test obtained throughout the trial.

Sharon Nachman, MD, PhD

If the child does not agree to be participating in this study, we will not enroll that child.

— Sharon Nachman, MD, PhD

Ethical Considerations

Along with the need for children’s inclusion and consent, ethically we also should consider the feelings of the children. They may feel fear, pain, or distress at any point of the trial. It is the responsibility of researchers and clinicians involved in the trial to minimize these concerns for both the child and the parents.

Parents or caregivers should be allowed to remain with the children wherever possible, and children’s concerns should be treated with sincerity and compassion.

Parental Considerations

If you are considering enrolling your child in a clinical trial, Nachman advises that parents ask as many questions as they can. She suggests the following is a good list of questions to consider:

  • What is the trial studying?
  • How many doses will my child get?
  • How often do you need to draw blood?
  • Who draws the blood?
  • Do they have experience with children?
  • How long should we expect to be involved?
  • Where and when are we expected to turn up?

Nachman also reminds parents that all clinical trial involvement is voluntary. You are able to pull out at any point should you or your child decide you don’t wish to participate anymore.

She also says, “Transparency is key.” Any information about the trial should be available to you, provided it doesn’t breach privacy laws or affect the study results.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.

2 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. National Centre for Immunisation Research and Surveillance (Australia). Phases of clinical trials.

  2. Joseph PD, Craig JC, Caldwell PHY. Clinical trials in children. Br J Clin Pharmacol. 2015;79(3):357-369. doi:10.1111/bcp.12305