RESUMEN
The global meridional overturning circulation (GMOC) is important for redistributing heat and, thus, determining global climate, but what determines its strength over Earth's history remains unclear. On the basis of two sets of climate simulations for the Paleozoic characterized by a stable GMOC direction, our research reveals that GMOC strength primarily depends on continental configuration while climate variations have a minor impact. In the mid- to high latitudes, the volume of continents largely dictates the speed of westerly winds, which in turn controls upwelling and the strength of the GMOC. At low latitudes, open seaways also play an important role in the strength of the GMOC. An open seaway in one hemisphere allows stronger westward ocean currents, which support higher sea surface heights (SSH) in this hemisphere than that in the other. The meridional SSH gradient drives a stronger cross-equatorial flow in the upper ocean, resulting in a stronger GMOC. This latter finding enriches the current theory for GMOC.
RESUMEN
This manuscript describes the process and impact of strengthening the WHO Regional Office for Africa (WHO AFRO)'s COVID-19 vaccination information system. This system plays a critical role in tracking vaccination coverage, guiding resource allocation and supporting vaccination campaign roll-out for countries in the African region. Recognising existing data management issues, including complex reporting prone to human error, compromised data quality and underutilisation of collected data, WHO AFRO introduced significant system improvements during the COVID-19 pandemic. These improvements include shifting from an Excel-based to an online Azure-based data collection system, automating data processing and validation, and expansion of collected data. These changes have led to improvements in data quality and quantity including a decrease in data non-validity, missingness, and record duplication, and expansion of data collection forms to include a greater number of data fields, offering a more comprehensive understanding of vaccination efforts. Finally, the creation of accessible information products-including an interactive public dashboard, a weekly data pack and a public monthly bulletin-has improved data use and reach to relevant partners. These resources provide crucial insights into the region's vaccination progress at national and subnational levels, thereby enabling data-driven decision-making to improve programme performance. Overall, the strengthening of the WHO AFRO COVID-19 vaccination information system can serve as a model for similar efforts in other WHO regions and contexts. The impact of system strengthening on data quality demonstrated here underscores the vital role of robust data collection, capacity building and management systems in achieving high-quality data on vaccine distribution and coverage. Continued investment in information systems is essential for effective and equitable public health efforts.