Background
Group B streptococcus (GBS) can cause invasive disease (iGBS) in young babies, usually presenting as sepsis or meningitis, and is also associated with stillbirth and premature birth. Vaccines against group B streptococcus (GBS) are in development, but their potential health impact and cost-effectiveness have not been evaluated globally.
Methods and findings
We assessed the health impact and value (using the net monetary benefit (NMB), which measures the economic and health effects of vaccination in monetary units) of maternal group B streptococcus vaccination (GBS) in an annual cohort of 140 million pregnant women in 183 countries in 2020.
Our analysis uses a decision tree model, which incorporates the risks of group B streptococcus (GBS)-related health outcomes from an existing Bayesian disease burden model. We extrapolated country-specific group B streptococcus (GBS)-related healthcare costs using data from a previous systematic review and estimated quality-adjusted life years (QALYs) lost due to infant mortality and long-term disability .
We assumed 80% vaccine efficacy against iGBS and stillbirth, following WHO preferred product characteristics, and coverage based on the proportion of pregnant women receiving at least 4 prenatal visits. One dose was assumed to cost $50 in high-income countries, $15 in upper-middle-income countries, and $3.50 in low/lower-middle-income countries.
Vaccination of pregnant women could prevent 127,000 (95% uncertainty range 63,300 to 248,000) cases of early-onset and 87,300 (38,100 to 209,000) cases of late-onset childhood group B streptococcus (GBS), 31,100 deaths ( 14,400 to 66,400), 17,900 (6,380 to 49,900) cases of severe neurodevelopmental impairment, and 23,000 (10,000 to 56,400) stillbirths.
An effective vaccine against prematurity associated with group B streptococcus (GBS) could also prevent 185,000 (13,500 to 407,000) preterm births. Globally, a 1-dose vaccine program could cost $1.7 billion but save $385 million in healthcare costs. The estimated global NMB ranged from $1.1 billion ($−0.2 billion to 3.8 billion) under the least favorable regulatory assumptions to $17 billion ($9.1 billion to 31 billion) under the most favorable regulatory assumptions.
The main limitation of our analysis was the paucity of data to inform some of the model parameters, such as those governing health-related quality of life and long-term costs of disability, and how these parameters may vary across the country contexts.
Conclusions
In this study, we found that maternal vaccination against group B streptococcus (GBS) could have a large impact on infant morbidity and mortality . Globally, a reasonably priced maternal GBS vaccine is likely to be a cost-effective intervention.
Why was this study done?
What did the researchers do and find?
What do these findings mean?
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Comments
Global Maternal Strep B Vaccination Program Could Save Millions and Prevent Thousands of Deaths Worldwide
A global maternal immunization program for group B streptococcus (B streptococcus) would save millions in healthcare costs by reducing death and disability, but without tiered pricing, equitable access will likely not be achieved. Several vaccines are currently being developed, and an evaluation of the impact and value of a global program will be published on March 14 in the open access journal PLOS Medicine. It finds that this could prevent more than 200,000 cases and more than 31,000 deaths, and reduce disability in children.
Strep B can infect pregnant women and their babies, causing sepsis and meningitis in newborns and sometimes leading to death or disability. It is linked to an increased risk of stillbirth and premature birth. As vaccines move closer to approval, a comprehensive economic assessment of vaccination will inform investment decisions in the development of additional vaccines, as well as guide financing and fair pricing.
Simon Procter of the London School of Hygiene & Tropical Medicine , UK, and colleagues developed a model to assess the cost-effectiveness of Strep B vaccines in 140 million pregnant women in 183 countries in 2020. They used recent global estimates of the burden of B strep health in pregnant women and their children and estimated costs to health systems, calculating quality-adjusted life years lost due to infant mortality and long-term disability.
Based on the World Health Organization’s published list of preferred characteristics for a Strep B vaccine, the team assumed that the vaccine would prevent infection in 80% of vaccinated women and that women who receive at least four prenatal visits would be vaccinated. . They assumed a cost of $50 per dose in high-income countries, $15 in upper-middle-income countries, and $3.50 in low- and lower-middle-income countries. Vaccination could prevent 127,000 cases of early-onset and 87,300 late-onset childhood iGBS, 31,100 deaths, 17,900 cases of moderate and severe neurodevelopmental impairment, and 23,000 stillbirths.
The study is limited by missing some data, such as the impact of Step B on health-related quality of life and long-term costs of disability, but estimates that a 1-dose vaccine schedule could cost $1.7 billion globally while saving $385 million in healthcare costs. The team warns that regional sensitivities to vaccine prices could affect policy decisions and that tiered vaccine pricing would allow for equitable access.
Dr. Procter adds: “By reducing serious group B streptococcal (GBS) infections, an effective maternal GBS vaccine deployed worldwide could prevent tens of thousands of newborn deaths and stillbirths each year. “Our findings suggest that maternal GBS vaccination could be cost-effective in most countries, and we hope this will encourage the additional investment needed to bring GBS vaccines to market.”
Discussion and final message
A global high-coverage maternal immunization program against group B streptococcus (GBS) could prevent hundreds of thousands of cases along with tens of thousands of deaths, stillbirths, and cases of long-term disability . We estimate that such a program could have a net cost of around $1.3 billion, with the majority of the costs in Europe and North America. However, it would be cost-effective in most countries under favorable assumptions, particularly if it can reduce preterm births.
Even under less favorable assumptions, a single-dose GBS vaccine could still be cost-effective due to additional factors that we did not explore. In some high-income countries, GBS vaccination plus current practice may be less cost-effective compared to current practice alone due to the lower incidence of GBS in infants due to PJI. However, GBS vaccination could allow high-income countries to achieve additional cost savings by revising PAR algorithms for vaccinated mothers. In low- and lower-middle-income countries, the incidence of iGBS may be higher, but so is the health opportunity cost of healthcare spending due to budget constraints leading to lower thresholds at which interventions can be considered profitable.
More competitive prices can allow vaccination to be profitable, even in the least favorable scenarios. Competitive and finely tiered vaccine prices could also be beneficial for manufacturers, as financial analyzes suggest that high global demand is needed to ensure that the development costs of a GBS vaccine can be recovered [46]. Our economic assessment can inform both manufacturers and donors investigating the financial viability of investing in the development of a GBS vaccine, as well as countries identifying the price they should be willing to pay for such a vaccine.
| Overall, our results suggest that high coverage of a competitively priced maternal GBS vaccine has the potential to save tens of thousands of lives worldwide and is likely to be a cost-effective investment, especially if the vaccine can reduce prematurity associated with GBS. |
