*4.2. Research Topics and Emerging Trends*

This study explores the research topics and emerging trends in the global health area mainly from two aspects: Keyword co-occurrence analysis and literature co-citation analysis. Keywords can clearly and intuitively reflect the research theme, core research content, and main research direction of an article. Therefore, in the fields of scientific text mining and scientometrics, the co-occurrence analysis of keywords can quickly grasp the development trends and research topics of a specific research field [49]. From the results of keyword co-occurrence analysis, there are five main research topics in the global health field, including global health goals and directions, research on global health risk factors, research on specific groups and specific countries or regions, and research on cooperative communication mechanisms. The goal of global health is to improve the equity of global health and the quality of life of people worldwide [50]. The original intention of the rise of global health is based on its effective way of dealing with global health inequity, which provides a new perspective and approach for achieving the goal of global health equity [51]. Global health focuses on the fairness and health influencing factors of global health, not just the health status and influencing factors of people in a specific country or region. Global health also pays attention to the global distribution of health and disease and its determinants, attaches importance to the impact of globalization on health and changes in the nature of global health governance, and emphasizes interdependence and coping strategies that transcend national and policy sector boundaries [52,53].

After literature citation analysis and cluster analysis, we learned that "global health governance", "global health diplomacy", "medical education", "global health education", "antimicrobial resistance" and "Zika Virus" are the current research frontiers and hot spots. Global health governance is a tool for dealing with the determinants of a healthy society across sectors [54]. The theoretical research and practical aspects of global health reflect that poor governance at the national and international levels will undermine the achievement of global health goals [55]. The catalyst for global health implementation is global health diplomacy. An important change in the 2000 G-8 summit was the linking of foreign policy with global health issues, and global health began to become a major goal and strategy of foreign policy. Global health diplomacy promotes the participation of various actors in the global governance actions taken to solve global health and related issues [56]. Some sovereign countries have established bilateral or multilateral global health strategies with other countries or organizations through mechanisms such as foreign policy and negotiation and consultation, formulated global health plans, and provided relevant financial and technical assistance to low- and middle-income countries [57].

Besides, "quality of life", "energy balance; adipose tissue; appetite", "subunit vaccine", "mental illness", "mental health", "community impact", "health services" and "interaction strategies" are important research topics and directions of global health. Combined with real-time news and past development experience, the current global outbreak of the new coronavirus in 2019 (COVID-19) has exposed many global health problems. Therefore, the prevention and control of infectious diseases, epidemiological studies of infectious diseases, international collaboration on global health, and health assistance will be a new research hotspot and emerging trends.

Despite the positive findings of the study, there are still some limitations. From the perspective of literature data, the literature data in this article only come from the Web of Science core collection database. Moreover, we only selected documents written in English. Secondly, this article does not contain grey literature, such as non-publicly published government documents, dissertations, non-publicly issued conference documents, scientific reports, technical archives, etc. From the perspective of visual analysis, this article does not interpret all the information in the knowledge graph. It is also one of the problems and directions that the follow-up research needs to think of and explore further.
