A new global analysis in Vaccines uses machine-learning counterfactuals to quantify just how much disease and economic burden has been averted by Hib vaccination over the past three decades. Drawing on data from 159 countries between 1990 and 2021, Zhou and colleagues apply a causal forest model to estimate what Hib-related deaths and disability-adjusted life-years (DALYs) would have been without vaccine introduction, controlling for economic growth and health system improvements. They estimate that Hib immunization has averted 1.32 million deaths (95% UI 32,034–2.72 million) and 90.97 million DALYs (95% UI 3.57–197.10 million) worldwide—about a 27% reduction in both outcomes. Health gains were especially pronounced in Africa and low-income countries, where later introduction combined with high baseline disease burden created a latecomer high-return pattern, with each dose yielding particularly large reductions in deaths and DALYs.
From an economic perspective, the authors find that Hib vaccination has generated substantial human capital gains and is cost-saving in all countries studied. Using a human capital approach, they show that the largest proportional economic benefits (as a share of 2021 GDP) accrue to small states and to African and other low- and middle-income settings, even though those same countries face higher vaccine costs relative to GDP and persistent access gaps. Equity analyses reveal that, despite global scale-up, Hib disease burden remains concentrated in LMICs and overall health inequality indices changed little—and may have worsened—because high-income countries introduced the vaccine earlier and reached high coverage. The paper also highlights China as the only country yet to include Hib in its national schedule: scenarios introducing Hib between 2026 and 2033 are all cost-effective, with earlier adoption projected to avert up to 3,440 deaths, 128,000 DALYs, and generate net economic gains of around USD 317 million, strengthening the case for prompt inclusion in China’s NIP and continued global support to close remaining Hib access gaps.
How can the findings be used?
This article will be immensely valuable to health systems policymakers and immunization service providers, as it highlights critical areas requiring attention. It also offers a foundation for researchers to further explore issues related to the health workforce, which serves as the cornerstone of effective service delivery.
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