The World Health Organization (WHO) on Wednesday called for the urgent development of a vaccine against a bacterial infection responsible for around 150,000 infant deaths and stillbirths every year.

A fresh report by the United Nations health agency and the London School of Hygiene and Tropical Medicine found that the impact of Group B Streptococcus (GBS) infection, which is estimated to live harmlessly in the intestinal tracts of up to a third of all adults, is a far bigger cause of preterm births and disabilities than previously thought.

The report confirmed a previous devastating finding from 2017 that the bacterium causes almost 100,000 newborn deaths and close to 50,000 stillbirths each year, although it pointed to significant data gaps suggesting the true figures could be higher.

And for the first time, it quantified the impact on preterm births, finding that GBS is behind more than half a million early deliveries each year, leading to significant long-term disabilities.

In light of such staggering numbers, the report authors lamented that more progress had not been made toward developing a vaccine.

"This new research shows that Group B strep is a major and underappreciated threat to newborn survival and wellbeing, bringing devastating impacts for so many families globally," Phillipp Lambach of WHO's immunization department said in a statement.

"WHO joins partners in calling for urgent development of a maternal GBS vaccine, which would have profound benefits in countries worldwide."

Professor Joy Lawn, who heads LSHTM's maternal adolescent, reproductive and child health center, agreed.

"Maternal vaccination could save the lives of hundreds of thousands of babies in the years to come," she said, decrying the lack of progress since the idea of developing a jab against GBS was first raised three decades ago.

On average, 15% of pregnant women worldwide, or nearly 20 million annually, carry the GBS bacterium.

But even though most of these cases show no symptoms, an infected pregnant woman can pass GBS to her fetus via the amniotic fluid, or during birth.

Babies and fetuses are particularly vulnerable because their immune systems are not strong enough to fight the multiplying bacteria.

If untreated, GBS can lead to meningitis and septicemia, which can be deadly. Babies that survive may develop cerebral palsy, or permanent sight and hearing problems.

Wednesday's report showed that the bacterium leaves some 40,000 infants each year with neurological impairments.

Currently, women with GBS are given antibiotics during labor to reduce the chance of it passing to their baby.

But this approach poses problems in places where screening and antibiotic administration during labor are less accessible.

Tellingly, the highest rates of maternal GBS are found in sub-Saharan Africa – which alone accounts for around half of the global burden – and Eastern and South-Eastern Asia, the study showed.

It suggested that a GBS vaccine could be administered to pregnant women during routine checkups and that if the rate reached over 70% of pregnant women, it could avert 50,000 infant and fetus deaths each year.