A Dose of Knowledge: Vaccine Trials for Children Compared to Adults

Written by: Sudil Mahendra, Associate Scientific Director

With COVID-19 vaccines currently under study for children under the age of 5, there has been a significant increase in discussion about vaccine trials in children. Parents and caretakers are often inundated with information about childhood vaccines, some of which is inadvertently or purposefully misleading. The challenging landscape of vaccine-related information underscores the importance of allaying fears about the process of childhood vaccine development and approval.

Vaccines for children have been developed, studied, and administered for more than 200 years. In the 18th century, the smallpox vaccine was the first to be administered to children. Additional vaccines were developed and routinely recommended for children throughout the 20th century and into the present day.1 As a result, vaccinations are estimated to prevent more than 21 million hospitalizations and 732,000 deaths among children born in the last 20 years. This equates to savings of nearly $295 billion in direct costs and $1.38 trillion in total societal costs.2

Researchers carefully design clinical trials in order to assess the dosing, safety, and efficacy of vaccines in adults. However, children have distinct physiological and developmental differences that affect the way they respond to infections and vaccines. For that reason, separate trials for children are necessary in order to gather essential data. Specifically, these clinical trials help to determine3:

  • The dose that balances generation of immunity with the lowest rate of side effects

  • The type of side effects experienced, as well as the frequency of those side effects

  • A correlate (or measurement) of protection, such as antibody levels, that can determine whether the vaccine is protective against infection (a correlate is not always identified)

Vaccine trials in children also require special ethical and clinical considerations. The study design must meet a higher standard before the investigators can enroll children. Clinical trials in children differ from those in adults in several ways4-6:

  • Enrolling children last in clinical trials: Vaccine trials in children can only begin after clinical trials in adults show that the vaccine is safe and effective

  • Requiring informed consent from parents and assent from children: Since children may not be able to fully understand the risks and benefits of participation in the clinical trial, their parents must provide consent for them by signing a form. Children are asked to give their verbal assent when possible

  • Studying safe and effective doses for different age groups: Researchers start at the lowest safest dose in the oldest age group, then test whether a larger dose is more effective or whether a lower dose still provides a complete response. After an ideal dose is found, the investigators begin assessing dosage again in a younger age group, until the ideal dose is found for each age group

Investigators must also ensure that the vaccine under study does not interfere with the immunity generated by any other routine childhood vaccines. Conversely, they must assess whether the routine vaccination protocols for children affect the immune response to the vaccine under study. As a result, vaccine trials in children take longer than adult studies.4,6

Once the trial is completed, the FDA reviews the results thoroughly to ensure the vaccine’s safety and efficacy in children. When they determine that the vaccine is safe and effective and its benefits outweigh its risks, it is approved for use. Then, medical and public health experts from the Advisory Committee on Immunization Practices (ACIP), American Academy of Pediatrics, and American Academy of Family Physicians may consider adding the vaccine to the recommended childhood immunization schedule. The ACIP continues to monitor the vaccine’s safety and efficacy data after its continuous use in the public in order to update recommendations as needed.7

While vaccine development, study, and approval are thorough in assessing safety and efficacy for adults, this process is under even more scrutiny for children. After this rigorous assessment, vaccines can help to keep children, families, and their surrounding communities safe from serious diseases.

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At Razorfish Health, we know what it takes to navigate the modern health care landscape. If you want to fuel your knowledge, please reach out to Delia.Pavlichko@razorfishhealth.com. We’re interested in hearing your perspective as well as your thoughts on upcoming communication challenges and opportunities.

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References:

  1. Offit P, ed. Vaccine history: Developments by year. Children's Hospital of Philadelphia. March 30, 3021. Accessed April 19, 2022. https://www.chop.edu/centers-programs/vaccine-education-center/vaccine-history/developments-by-year

  2. Centers for Disease Control and Prevention. Report shows 20-year US immunization program spares millions of children from diseases. April 24, 2014. Accessed April 19, 2022. https://www.cdc.gov/media/releases/2014/p0424-immunization-program.html

  3. Children's Hospital of Philadelphia. Feature article - COVID-19 vaccines: Clinical trials in children. August 10, 2021. Accessed April 19, 2022. https://www.chop.edu/news/feature-article-covid-19-vaccines-clinical-trials-children

  4. Paturel A. Understanding COVID-19 vaccine trials in children. Cedars Sinai. July 13, 2021. Updated November 8, 2021. Accessed April 19, 2022. https://www.cedars-sinai.org/blog/covid-19-vaccine-trials-children.html

  5. National Institutes of Health. Ensuring vaccine safety for children. October 26, 2021. Updated November 4, 2021. Accessed April 19, 2022. https://covid19.nih.gov/news-and-stories/ensuring-vaccine-safety-children

  6. Lucci-Canapari J, Forman R. COVID-19 vaccine trials for young children proceed at Yale. Yale School of Medicine. April 23, 2021. Accessed April 19, 2022. https://medicine.yale.edu/news-article/covid-19-vaccine-trials-for-young-children-proceed-at-yale/

  7. Centers for Disease Control and Prevention. The journey of your child's vaccine. January 26, 2018. Accessed April 19, 2022. https://www.cdc.gov/vaccines/parents/infographics/journey-of-child-vaccine.html

Paula Cuerquis