Pfizer Group B strep vaccine for infants returns encouraging mid-stage trial results
Streptococcus agalactiae bacteria, responsible for vaginal and urinary tract infections and newborn infections including meningitis and septicemia. Optical microscopy view.

Pfizer on Wednesday said its experimental vaccine targeting the potentially deadly bacterial disease Group B Streptococcus returned strong mid-stage clinical trial results, a promising step as the drug inches toward potential approval.

Pfizer is among several drugmakers racing to develop the world's first shot targeting Group B strep disease, which is linked to nearly 150,000 infant deaths worldwide each year, especially in lower-income countries.

The Food and Drug Administration in September granted breakthrough therapy designation to Pfizer's vaccine, which is intended to expedite the development and review of the shot.

Pfizer's single-dose shot generated antibodies that may provide infants with meaningful protection against the disease, according to the data released Wednesday from a phase two clinical trial.

The jab is administered to expectant mothers, who pass vaccine-induced antibodies to their fetuses. One of the company's vaccines targeting respiratory syncytial virus also uses that maternal vaccination method.

Pfizer's encouraging phase two trial results provide hope that maternal vaccination against the disease, also known as GBS, could help prevent thousands of cases in babies.

The results will also help the company plan its phase three clinical trials on the shot, which are typically required before the FDA approves a drug.

The Bill & Melinda Gates Foundation, which supported the phase two trial, provided an additional $100 million grant to Pfizer last year that will fund late-stage trials and help facilitate the delivery of shots to lower-income countries following a potential approval.