A Study to Learn About Group B Streptococcus Vaccine in Healthy PregnantWomen and Their Infants

• Research type

  Research Study

• Full title

  A Phase 3, Randomized, Placebo-Controlled, Double-Blinded Trial to Evaluate the Safety, Tolerability, and Immunogenicity of a Multivalent Group B Streptococcus Vaccine in Healthy Pregnant Women and Their Infants

• IRAS ID

  1012260

• Contact name

  Steve Paul Moran

• Contact email

  Stephen.P.Moran@pfizer.com

• Sponsor organisation

  Pfizer Inc.

• Research summary

  Group B streptococcus (GBS) is found in about 1 in 5 pregnant women. It can be passed to babies in the womb, at birth, and after. GBS can cause life-threatening illnesses in babies like sepsis (blood infection), meningitis (brain infection) and pneumonia (lung infection). Even with treatment, invasive GBS infection in babies can lead to long-term health problems, including seizures, hearing and vision loss.
  This trial is to learn about the safety of an investigational vaccine called GBS6 in pregnant women and their babies, and how it could protect them from the 6 most common types of GBS.
  Healthy pregnant women in the study are: 1) aged 49 or younger and between gestational age of 24 and 36 weeks (“Gestational age” is a medical term used to describe how far along a pregnancy is; 2) had a fetal ultrasound examination performed no earlier than 18 weeks of gestation with no major fetal abnormalities observed; 3) negative for HIV, Hepatitis B and syphilis.
  Pregnant participants will receive only 1 shot in an arm. This could either be GBS6 or placebo (salt water). Placebo is an inactive substance used for comparison purposes. Blood samples will be taken before the shot, at 1 month after, and at delivery. Baby’s cord blood samples will be collected at birth. These samples are used for antibody testing. The pregnant participants may take part in this study for a maximum of 14 months (6 months after delivery), and their babies for about 12 months after they are born. The pregnant participants and their babies will need to visit the research site at least 3 to 4 times with some visits permitted to occur over the telephone. To conduct this trial, at least an obstetrician and a paediatrician are preferred at each site.

• REC name

  East of Scotland Research Ethics Service REC 2

• REC reference

  25/ES/0068

• Date of REC Opinion

  4 Sep 2025

• REC opinion

  Further Information Favourable Opinion