Fractional dosing of vaccines is considered a dose sparing solution for situations of vaccine shortages. Lower doses of vaccines, typically as 1/5th of the standard dose, are at present used for vaccines such as rabies, inactivated polio and yellow fever vaccines. However, the immunogenicity and safety of fractional doses compared to full dose need to be established before this strategy can be used. Since 2016, Epicentre has been working on assessing fractional doses of yellow fever vaccines. The aim of these studies is to provide the needed evidence to recommend fractional dosing of YF vaccines for outbreak response, when there are insufficient standard doses to protect the population at risk.
A non-inferiority trial assessing the non-inferiority of fractional doses of the four WHO-prequalified yellow fever vaccines in a general adult population, children and HIV+ adults has been recently completed in Uganda and Kenya. To complement these, a study looking at the non-inferiority of lower doses of the yellow fever vaccine manufactured by Institut Pasteur Dakar is currently ongoing. Several factors have been considered in the design of these studies to ensure that the results are sufficient for policy and practice change. These include the fraction to be studied, the study design and goal, evaluation of vaccine protection and practical aspects related to the administration of the vaccine.
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At the time of writing, many people around the world are feeling the pain, disruption, and devastating health consequences driven by climate change. The world has been shocked by the widespread flooding in Europe and the consecutive catastrophic hurricanes in North America. Yet far less attention is given to the impacts of climate change in places where Médecins Sans Frontières (MSF) works, such as Central African Republic, Chad, Côte d’Ivoire, Democratic Republic of Congo, Myanmar, Niger, Nigeria, and South Sudan. In 2024, these populations have likewise been affected by devastating floods, many of them not for the first time.
Although immediate impacts like injury, displacement, and limited access to healthcare may be similar worldwide, the compounding crises that follow and the capacity to recover from these vary significantly. Individuals in low-resource and humanitarian settings face significant health threats while contributing the least to global emissions. These regions are often vulnerable to climate hazards and possess low adaptive capacity, increasing people’s susceptibility to the negative impacts of climate change.
In this brief, drawing on evidence from indicators in the 2024 report of the Lancet Countdown on Health and Climate Change, MSF teams present examples of how climate change and environmental degradation are making provision of assistance more difficult by amplifying health and humanitarian needs and by further complicating interventions. It also highlights activities that respond to the climate crisis using a three-pillar approach: mitigating MSF’s environmental footprint, adapting healthcare delivery and emergency response to the current and future realities of climate change, and advocating for those impacted.
The complexity of climate change and environmental degradation, coupled with highly politicised and siloed global response efforts often make it insufficiently clear to health and humanitarian implementing partners that every issue is part of a continuous process, where each component informs the others. In this brief, MSF staff outline six focus areas where teams are engaged in developing environmentally-informed health and humanitarian interventions, emphasising their interdependence, and how failure to act on one issue not only impedes progress on that specific component but also affects the entire sequence of subsequent actions.