STREPTOCOCCUS AGALACTIAE, SEROTYPE IV, CAPSULAR POLYSACCHARIDE, CONJUGATED TO CRM197

Table of contents

• What is Streptococcus Agalactiae?
• How does the GBS6 vaccine work?
• Which conditions is it used or studied for?
• How is the GBS6 vaccine given?
• What do the clinical trials show?
• What side effects are known?

What is streptococcus agalactiae?

Streptococcus Agalactiae, also known as group B streptococcus (GBS), is a bacterium that can cause serious infections, particularly in newborn infants. The full name of the vaccine studied in the trial is Streptococcus Agalactiae, serotype IV, capsular polysaccharide, conjugated to CRM197, but the vaccine used in this trial is a 6-valent polysaccharide conjugate vaccine called GBS6 that covers six serotypes: Ia, Ib, II, III, IV, and V.^[1] GBS6 is an investigational vaccine, meaning it has not yet been authorised as a medicine for general use.

How does the GBS6 vaccine work?

GBS6 is designed to stimulate the mother's immune system to produce antibodies against the capsular polysaccharides (CPS) that form the outer coating of six GBS serotypes. These antibodies can cross the placenta during pregnancy and reach the infant before birth. The trial measures serotype-specific anti-CPS IgG antibody concentrations in infant participants at birth to see whether the levels are high enough to provide protection against invasive GBS disease.^[1] The vaccine uses CRM197 as a carrier protein, a technique that helps the immune system respond more strongly to the polysaccharide part of the vaccine.

Which conditions is it used or studied for?

GBS6 is being studied for the prevention of group B streptococcus (GBS) disease in infants. The trial focuses on two forms of the disease:

• Early-onset GBS disease (EOD) — an infection that appears in the first week of life, usually within the first 24 to 48 hours after birth.
• Late-onset GBS disease (LOD) — an infection that develops between the first week and the first three months of life.

Both forms can cause serious conditions such as sepsis, pneumonia, and meningitis in newborns. The trial aims to assess whether maternal vaccination during pregnancy can protect infants from both forms of the disease.^[1]

How is the GBS6 vaccine given?

The GBS6 vaccine is given as an intramuscular injection to healthy pregnant women during pregnancy. The trial record lists the intervention as a solution with a concentration of 00 Aµg/ml microgram(s)/millilitre, administered intramuscularly. The placebo arm receives a matching intramuscular injection.^[1] The exact timing and number of doses during pregnancy are part of the trial design and are not detailed in the registry record.

What do the clinical trials show?

The clinical trial programme for GBS6 currently consists of one authorised Phase 3 trial. This is a large interventional study with a planned enrollment of 12,000 participants, making it one of the largest trials of a maternal GBS vaccine to date.^[1] The trial is authorised but not yet recruiting, meaning it has received regulatory approval to begin but has not started enrolling participants.

What is the trial measuring?

The trial measures several types of outcomes. The primary outcomes include prespecified local reactions at the injection site such as redness, swelling, and pain, as well as prespecified systemic events including fever, nausea, vomiting, diarrhea, headache, fatigue, muscle pain, and joint pain.^[1] The trial also records adverse events, serious adverse events, medically attended adverse events, and adverse events of special interest. In addition, the trial measures serotype-specific anti-CPS IgG antibody concentrations in infant participants at birth, which are used to estimate the predicted vaccine efficacy for both early-onset and late-onset GBS disease.^[1]

Who can take part in the trial?

The trial enrols healthy pregnant women and follows their infants after birth. The maternal participants receive either the GBS6 vaccine or a placebo during pregnancy, and the safety and antibody levels of both mothers and infants are assessed.^[1]

What side effects are known?

The trial is designed to collect information on side effects, but no side effect data from this trial are yet available because the study is authorised and not yet recruiting. The registry record lists the types of events that will be monitored: local reactions at the injection site, systemic events such as fever and headache, adverse events, serious adverse events, medically attended adverse events, and adverse events of special interest.^[1] Until the trial reports results, no side effect profile for GBS6 can be described.