Though most children aren’t seriously harmed by COVID-19, some do become very sick. With new COVID-19 variants continuing to emerge, getting vaccinated can help protect your child from serious illness. If you are thinking about vaccinating your child against COVID-19 for the first time, consider joining our ongoing vaccine clinical trial.

This study will help us learn how well our updated COVID-19 vaccine works in children who have not been previously vaccinated and see if the number of recommended doses can potentially be reduced for children under the age of 5. The study vaccine has been authorized by the United States Food and Drug Administration for children at least 6 months of age. It is designed to protect against the newer COVID-19 variant called XBB.1.5.

Your child’s participation in this study could reduce their risk of getting COVID-19. It will also help to improve the vaccine options available to protect children around the world against the newest COVID-19 variants.

Who may participate

Joining a clinical trial is an important and personal decision. We thank you for considering participation as an option that may be right for your family. 

This study is enrolling children 2 to 4 years old who have not been vaccinated for COVID-19. To see if your child may qualify to participate, click ‘Get Started’.

If your child is under 2 or over 4 years old, they may qualify for one of our other COVID-19 vaccine studies. Click here to learn more about our currently enrolling COVID-19 vaccine studies.


2 – 4 years

Current vaccination status

No prior vaccines for COVID-19

Each clinical study has its own guidelines for who can participate, called eligibility criteria. However, only the research study staff can determine if your child qualifies to enroll in the study.

Get started — See if you may be eligible

Answer a 2-minute questionnaire.

A first step as you consider this study is to answer a 2-minute online questionnaire about your child’s health and medical history. If your answers show the study might be a good fit for your child, you may choose to have your contact information shared with a Pfizer Clinical Trial Contact Center Navigator.

Speak with a study representative.

If you’re interested, a Pfizer Clinical Trial Contact Center Navigator will call you and do a more detailed review of the study and your child’s medical history to see if they may be able to participate and be referred to a study clinic that you select.

Confirm your child’s eligibility.

Your answers to these questions will only be linked to you if your responses indicate that your child may be eligible to participate in this study and you choose to share your contact information with the study team. Pfizer study team members and our partners will have access to reports containing aggregated data that will not be directly linked back to you or your child. Only the study staff can determine if your child meets the study’s eligibility criteria and is able to enroll in the study.

What to expect

If your child is eligible to participate, they will receive a single dose of the study vaccine at their first visit.

Your child’s health will be carefully monitored by the study team until 6 months after their vaccination, and they will have 2 follow-up visits over the course of the study.

There is no cost to participate in this study, and health insurance is not required. You will also be compensated for completing study-related activities.

Number of vaccine doses

1 dose

Study visit schedule

At least 3 visits over 6 months. Some visits will be at the study clinic and others may be done by phone.

Help make a difference

Rates of severe disease and hospitalizations for COVID-19 vary greatly by age for children, with children under 5 years having the greatest risk of being hospitalized.1 Race and ethnicity, family income levels, and where they live can also increase a child’s risk for severe illness.2, 3 That is why it is important that children of all backgrounds participate in this study – to reflect the diversity of families around the world looking for better protection against COVID-19.

Help make a difference

Mother and daughter – Pfizer Clinical Trials
Mother and daughter – Pfizer Clinical Trials

Frequently asked questions

What are the possible side effects?
As with any vaccine, local reactions at the injection site can be common – such as redness, swelling, or pain. There is also potential for other symptoms like a mild fever or fatigue. The known side effects will be further explained in the informed consent document and discussed with you by the study doctor before you consider having your child join the study. If there is any new information that we learn about the study vaccine during the clinical trial, the study doctor will share that with you as well.
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Will my child receive a placebo?
All children will receive the updated COVID-19 vaccine in this study. No children will receive a placebo (vaccine with no active ingredients).
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What kinds of tests and procedures are you going to perform?
At the beginning of the clinical trial, the study doctor will check your child’s overall health and medical history to see if this study is a good fit for them. Your child may also have their blood drawn twice during the trial. The study team will give you more information about the tests and procedures during the review of the study’s informed consent document
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1. COVID Data Tracker. CDC. Consultado el 11 de enero de 2024.
2. Children and COVID-19: State-Level Data Report. American Academy of Pediatrics. Actualizado el 15 de mayo de 2023. Consultado el 28 de septiembre de 2023.
3. Obe A, et al. The Impact of the COVID-19 Pandemic on Black Children: A Two-Year Assessment. Black Coalition Against COVID. Marzo de 2023. Consultado el 6 de noviembre de 2023.

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