A deadly disease for infants has no vaccine—we’re changing that

Group B Streptococcus (GBS), a leading cause of sepsis and meningitis in young infants worldwide, is a bacterial infection that is common and generally harmless in adults but deadly in young infants—sometimes affecting babies just a few hours old. Even those that survive GBS infection are often left with lifelong disabilities such as deafness, blindness, and developmental impairments.

Nearly 20 percent of women worldwide have the GBS bacterium, which can live in the gastrointestinal tract and the vagina and be passed to baby around birth. Infections acquired this way (called "early-onset disease") can be managed, to some extent, by screening pregnant women and administering prophylactic antibiotics during labor if they’re found to be GBS carriers.

This strategy is expensive and logistically challenging, though, especially for low-resource countries. And GBS prevention simply isn’t that straightforward. All infants—even those born healthy to women that don’t carry the bacterium—are vulnerable to late-onset GBS disease in the days, weeks, and months following birth.

Moreover, antibiotics delivered during labor would be of little help in preventing the problems that can arise earlier in pregnancy. Not to mention, administering prophylactic antibiotics can contribute to antibiotic overuse and resistance.

To truly protect infants from GBS disease, we need a vaccine. And we need one that can protect them before they’re even born.

No vaccine currently exists to protect against GBS, though the tide is turning. Several vaccines are in the development pipeline with different manufacturers, and a GBS vaccine could become a reality in the coming years.

We’re doing our part to increase the odds. Since 2016, PATH and Seattle-area biotechnology company Inventprise Inc. have been working to develop a vaccine against GBS that can be delivered during pregnancy, thus allowing protective antibodies to pass from the pregnant woman to the baby in utero.

With funding from the Gates Foundation, we’re pursuing a multivalent conjugate vaccine—a vaccine that targets the most common strains of the disease and uses the most advanced technology. The vaccine candidate for this study covers six different GBS strains, including the five most common strains globally and a sixth that is currently seen in south Asia.

These details are important; research shows that a vaccine targeting five of the most common GBS strains would prevent 99 percent of GBS-related stillbirths and between 98 and 99 percent of GBS cases globally. A safe, effective GBS vaccine could have massive impact.

Vaccine development is a long and complex process, but we’ve reached a crucial milestone: a Phase 1/2, first-in-human study of Inventprise’s vaccine candidate began in November 2024 at New York University’s Langone Health Vaccine Center. Additional sites at University of the Witswatersrand Vaccines and Infectious Diseases Analytics Research Unit in Johannesburg, South Africa will join the study in early 2025. Between New York and South Africa, the vaccine candidate will be delivered to 600 healthy, non-pregnant women between 18 and 49 years of age.

Earlier stage clinical studies like this one examine the safety, tolerability, and performance of a vaccine, and are one step on the pathway toward approval and availability. They pave the way for larger studies that examine the vaccine’s performance in the populations it is designed for.

Importantly, this vaccine candidate is being designed to be accessible globally—especially to countries with low- and middle-income economies—which ensures that access isn’t dependent on geography.

GBS disease occurs worldwide, but the disease burden is significantly higher in countries with low-income economies—partly due to the lack of availability and feasibility of preventative screenings.

In high-income countries, the GBS mortality rate in infected infants is estimated to be between 6 and 14 percent, but in low- and middle-income countries, it’s estimated to be between 10 and 60 percent—a stark difference that highlights the inequity in access to health care resources like screening and treatment. Sub-Saharan Africa, in particular, is hard hit; studies estimate that nearly half of all GBS-related infant deaths globally occur there alone.

A GBS vaccine has huge potential all over the world but would have the greatest impact in these low-resource countries that have limited access to existing screening and treatment options. A GBS vaccine, developed specifically with low-resource countries in mind, would provide infants with the crucial protection they need against GBS. It would help reduce the number of pregnancies compromised by the disease and help to address the inequality in who is affected by this disease.

For PATH, this was an essential consideration when building our GBS vaccine development program; because, ultimately, simply being able to prevent disease doesn’t make a vaccine successful. Not if the people who need it the most can’t access it.

It’s why the vaccine we’re studying incorporates a disease strain that currently only impacts people living in south Asia. It’s why we’re studying the vaccine in South Africa—a country that suffers one of the highest GBS disease burdens in the world—with partners who know all too well the lasting damage and heartbreak this disease can bring.

No one should have to lose a pregnancy, experience a stillbirth, or watch their child suffer simply because of where they live.

The impacts of this program could extend far beyond the disease at hand. GBS is one of the four major causes of bacterial meningitis worldwide. A World Health Organization initiative to Defeat Meningitis by 2030 champions the development of affordable vaccines against these four diseases—which means this GBS vaccine development project aligns with global health priorities, and has the potential to address not one but two deadly diseases of global significance.

We still have a long road ahead, but bringing a vaccine candidate into clinical study is a major win that brings us one step closer to making lasting improvements in global maternal and child health. We look forward to a future where preventing death and disability from GBS disease is as simple as a quick prick in the arm.