As a parent, you know the danger that respiratory syncytial virus (RSV) can pose for your little one. Pfizer’s RSV vaccine (called ABRYSVO®) was the first vaccine approved for use in pregnancy to help protect newborns against RSV until they are 6 months old.

We’re currently researching if a single dose of our RSV vaccine given during a pregnancy continues to offer protection in subsequent pregnancies. The Marguerite study will help us determine how long protection lasts from the first maternal dose and whether a second dose is needed during later pregnancies.

Who may participate

If you are pregnant, you may be able to join the Marguerite study if you: 

  • Are between 18 and 49 years of age
  • Received a dose of Pfizer’s RSV vaccine during a previous pregnancy
  • Are expecting a single healthy baby
  • Are able to be vaccinated during weeks 32-36 of your pregnancy 

We are also enrolling a group of participants who are not currently pregnant that received a dose of Pfizer’s RSV vaccine during a previous pregnancy. 

These are not the only qualifications needed to be in this study. Our study team will be glad to give you all the details to help you decide if the study is right for you.

Condition

Respiratory syncytial virus (RSV)

Vaccination status

Received a dose of Pfizer’s RSV vaccine during a previous pregnancy

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

What to expect

If you are eligible and choose to join this study, the visit schedule will vary depending on whether you are pregnant. The research team will explain more about what will happen during the study, including potential benefits and risks, and answer any questions you may have. Participation is completely voluntary, and you can leave the study at any time.

Pregnant Participants and Their Babies

  • You will receive 1 dose of the RSV vaccine or placebo during weeks 32-36 of your pregnancy. A placebo looks like the study vaccine but has no active ingredients.
  • After receiving your vaccination, you will continue in the study until about 6 months after your baby is born. You will have about 4-5 visits, and your baby will have up to 4 visits.
  • We know nothing is more important to you as a parent than your baby’s wellbeing. Your health and your baby’s health will be carefully monitored throughout the study.

Non-Pregnant Participants

  • You will have a blood sample collected at the clinic to check how many RSV antibodies you have from your prior vaccination.
  • The study team will also call you a couple of days after your visit to check on your health.

Visit schedule for pregnant participants

A total of 8-9 study visits over about 7-10 months

Visit schedule for non-pregnant participants

A total of 2 study visits over about 2 days

Study-related costs

No cost to participate, and you will be paid for your time in the study

About RSV

Respiratory syncytial virus (RSV for short) is a serious risk to millions of babies every year. It can lead to symptoms such as:

  • Fever
  • Wheezing
  • Difficulty breathing
  • Trouble eating

Babies are more likely to get very sick or be hospitalized with RSV than older children and adults. Those younger than 6 months are the most vulnerable, making up more than half of all RSV-related deaths in hospitals.1 RSV also causes a significant number of illnesses in the first 5 years of life.

Fortunately, there are now maternal vaccines available that can help to prevent serious RSV illness in babies after they are born.

References:
1. Li Y, Wang X, Blau DM, et al. Global, regional, and national disease burden estimates of acute lower respiratory infections due to respiratory syncytial virus in children younger than 5 years in 2019: a systematic analysis. Lancet. 2022;399(10340):2047-2064.

Watch a short video to learn more about the Marguerite study

This short video explains what will happen during the Marguerite study to help you decide if joining is right for you and your baby.

Your family could make a difference

It’s important to have vaccines that can prevent infection and illness for all babies. To develop better vaccines for everyone, we need families of all backgrounds to get involved in vaccine research. 

Taking part in this study may help improve vaccine protection not only for your baby, but also other babies in the future. Thank you again for considering this clinical trial.

Clinical trials can lead to life-saving vaccines, but they can’t happen without you.

Your family could make a difference

Pregnant mother with her young son touching her stomach    – Pfizer Clinical Trials
Pregnant mother with her young son touching her stomach    – Pfizer Clinical Trials

Frequently asked questions

Why is this study important?

RSV is a risk to millions of babies every year. In a previous study, researchers found that Pfizer’s maternal RSV vaccine was able to prevent serious RSV disease in newborns. Now, we’re evaluating a second dose for expecting mothers who already received the RSV vaccine in their last pregnancy.

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Isn’t my baby already protected?

Pfizer’s maternal RSV vaccine has been approved to protect newborns after their parent receives 1 dose of the vaccine while pregnant. Additional research is needed to understand if the first dose offers protection for the next baby against serious RSV infection or if another dose will be needed. The Marguerite study will help decide if parents should receive another dose of the RSV vaccine when they are pregnant again.

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What is RSV?

[This question and answer will not be included when Option 1 for Area 6 is being used.] 

Respiratory syncytial virus (RSV for short) is a serious risk to millions of babies every year. In babies, RSV infections can lead to symptoms such as fever, wheezing, difficulty breathing, and trouble eating.

Babies are more likely to get very sick or be hospitalized with RSV than older children and adults. Those younger than 6 months are the most vulnerable, making up more than half of all RSV-related deaths in hospitals.1 RSV also causes a significant number of illnesses in the first 5 years of life.

References: 

1. Li Y, Wang X, Blau DM, et al. Global, regional, and national disease burden estimates of acute lower respiratory infections due to respiratory syncytial virus in children younger than 5 years in 2019: a systematic analysis. Lancet. 2022;399(10340):2047-2064.

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Is there a chance I could receive a placebo?

f you are pregnant and meet the requirements for the study, you will be enrolled into 1 of 2 vaccination groups. All participants in the first group will receive the study vaccine. In the second group, half of participants will receive the study vaccine and half will receive placebo. The placebo looks like the study vaccine but contains no active ingredients. The study team will let you know if you are part of group 1 or group 2 prior to receiving your study vaccination.

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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 joining 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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