Updated
October 7th, 2019

Hexavalent Group B Streptococcus Vaccine Candidate Found Protective

Pfizer GBS6 conjugate vaccine is targeted for the prevention of infant GBS invasive disease by maternal immunization

Pregnant mom with heart shaed hands

The results from a First-in-Human clinical study of a Hexavalent Group B Streptococcus (GBS6) conjugate vaccine were found to be positive.

This Phase 1/2 clinical study reported on September 17, 2019, the Multivalent Group B streptococcus vaccine candidate from Pfizer met the study’s end-points.

The GBS6 vaccine was reported well-tolerated in healthy adults and elicited robust immune responses for all at all dose levels and formulations that persisted through 6 months post-vaccination in healthy adults between the ages of 18-49 years.

This Phase 1/2 study is a placebo-controlled, observer-blinded dose-escalation trial, subjects (364) were randomized to receive a single dose of GBS6, formulated with or without AlPO 4, or saline placebo. 

The primary objective of this study was to describe the safety of GBS6, assessed by prompted local and systemic reactogenicity for 14 days after vaccination and unprompted adverse events (AEs) for up to 6 months depending on the severity of the adverse event.

For the 312 GBS6 recipients, the most common injection site reaction was pain and the most common systemic reactions were fatigue and headache. Adverse events were reported by 21% to 48.1% of GBS6 recipients across groups, compared to 38.5% of placebo recipients.

Few recipients had serious adverse events during the 6 months of the study.

The secondary objective was to describe the immunogenicity as measured by GBS6 serotype-specific IgG geometric mean concentrations (GMCs) before and after vaccination.

GBS6 was reported to elicit robust immune responses for all recipients at all dose levels and formulations that persisted through 6 months after vaccination. 

These researchers concluded saying ‘ this study supports the evaluation of GBS6 in pregnant women’ in future studies.

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Currently, there is a larger ongoing Phase 2 study for a Multivalent Group B streptococcus vaccine sponsored by Pfizer. 

Group B streptococcus (GBS) is an important cause of invasive disease in young infants. In the United States, GBS bacteria are a leading cause of meningitis and bloodstream infections in a newborn’s first 3 months of life, says the Centers for Disease Control and Prevention (CDC).

Infants born to women with sufficient pre-existing anti-GBS capsular IgG antibodies are at reduced risk of GBS disease. 

But, newborns are at increased risk for GBS disease if their mother tests positive for the bacteria during pregnancy. 

In newborns, GBS manifests as sepsis, pneumonia, and meningitis, with potentially fatal outcomes for some, and long-lasting neurological damage in about 46 percent of those infected.

And, case fatality rates are higher globally, 6-14% in high-income countries and 6-47% in low and middle-income countries.

Which means maternal immunization is an attractive disease prevention strategy for infants.

This study’s results are available via a PDF upon request.

These researchers work for Pfizer, Inc. Kimberly J. Center, M.D., Senior Director, Vaccine Clinical Research and Development, Pfizer, lead this study.

Published by Precision Vaccinations