Inequity in the access to and deployment of the coronavirus disease 2019 (COVID-19) vaccines has brought about great challenges in terms of resolving the pandemic. Aiming to analyze the association between country income level and COVID-19 vaccination coverage and explore the mediating role of vaccination policy, we conducted a cross-sectional ecological study. The dependent variable was COVID-19 vaccination coverage in 138 countries as of May 31, 2021. A single-mediator model based on structural equation modeling was developed to analyze mediation effects in different country income groups. Compared with high-income countries, upper-middle- (β = −1.44, 95% CI: −1.86–−1.02, p < 0.001), lower-middle- (β = −2.24, 95% CI: −2.67–−1.82, p < 0.001), and low- (β = −4.05, 95% CI: −4.59–−3.51, p < 0.001) income countries had lower vaccination coverage. Vaccination policies mediated 14.6% and 15.6% of the effect in upper-middle- (β = −0.21, 95% CI: −0.39–−0.03, p = 0.020) and lower-middle- (β = −0.35, 95% CI: −0.56–−0.13, p = 0.002) income countries, respectively, whereas the mediation effect was not significant in low-income countries (β = −0.21, 95% CI: −0.43–0.01, p = 0.062). The results were similar after adjusting for demographic structure and underlying health conditions. Income disparity remains an important cause of vaccine inequity, and the tendency toward “vaccine nationalism” restricts the functioning of the global vaccine allocation framework. Stronger mechanisms are needed to foster countries’ political will to promote vaccine equity.

In a microarray study, we found that hepatic miR-291b-3p was significantly increased in leptin-receptor-deficient type 2 mice (db/db), a mouse model of diabetes. The function of miR291b-3p is unknown. The potential role of miR-291b-3p in regulating hepatic lipid metabolism was explored in this study. High-fat diet (HFD)-and chow-fed mice were injected with an adenovirus expressing a miR-291b-3p inhibitor and a miR291b-3p mimic through the tail vein. Hepatic lipids and lipogenic gene expression were analyzed. Additionally, gain-and loss-of-function studies were performed in vitro to identify direct targets of miR-291b-3p. MiR-291b-3p expression and the protein levels of sterol regulatory element-binding protein 1 (SREBP1) and fatty acid synthase (FAS) were increased in the steatotic liver of db/db mice and HFD-fed mice versus their respective controls. Inhibition of hepatic miR-291b-3p expression prevented increases in hepatic lipogenesis and steatosis in HFD-fed mice. The opposite was observed when miR-291b-3p was overexpressed in the livers of chow-fed C57BL/6J wild-type mice. In vitro studies revealed that silencing of miR-291b-3p in NCTC1469 hepatic cells ameliorated oleic acid/palmitic acid mixture-induced elevation of cellular triglycerides. Importantly, we identified AMP-activated protein kinase (AMPK)-␣1 as a direct target of miR-291b-3p. Using metformin, an activator of AMPK, we showed that AMPK activation-induced inhibition of hepatic lipid accumulation was accompanied by reduced expression of miR-291b-3p in the liver. Liver miR-291b-3p promoted hepatic lipogenesis and lipid accumulation in mice. AMPK␣1 is a direct target of miR-291b-3p. In conclusion, our findings indicate that miR-291b-3p promotes hepatic lipogenesis by suppressing AMPK␣1 expression and activity, indicating the therapeutic potential of miR-291b-3p inhibitors in fatty liver disease.

The outbreak and global pandemic of COVID-19 have attracted a great deal of attentions to the problem of travel health. Cruise tourism is increasingly popular, with an estimated 30 million passengers transported on cruise ships worldwide each year. Safeguarding the health of cruise travelers during the entire travel is of ultimate importance for both the industry and global public health. Up to April 2020, nearly thirty cruise ship voyages had reported COVID-19 cases. The Diamond Princess, Grand Princess and Ruby Princess cruise ship had over 1400 total reported COVID-19 cases, and more than 30 deaths. Travel health transcends national borders and involves multilevel actors, thus needs global cooperation and governance. The global governance framework including problems, values, tools or regulations, and actors related to travel health were used to analyze the issues involved. Regulations and legislation at global and country level are required to prevent large-scale humanitarian crisis on travel health. Multilateral coordination, cooperation and collaboration mechanisms between governments, intergovernmental organizations, non-governmental organizations and industry are needed to build a better community of common destiny for travel health.

ObjectivesCognitive impairment is a precursor of dementia. This study aimed to examine the association of social engagement with cognitive decline during the process of normal ageing.MethodsWe used data from the China Health and Retirement Longitudinal Study. The cognitive functions were tested at baseline, and 2-year and 4-year follow-up visits. Social engagement was constructed as a comprehensive measure including the quantity and frequency of social activities. Activities of social engagement were classified into three types. Multilevel logistic model was fitted to evaluate the prospective association between social engagement and cognitive impairment.ResultsAfter 2-year follow-up, compared with participants with the lowest level of social engagement, those with level-2, level-3 and level-4 social engagement had a 12% (OR=0.88, 95% CI 0.71 to 1.09, p=0.242), 17% (OR=0.83, 95% CI 0.71 to 0.97, p=0.020) and 25% (OR=0.75, 95% CI 0.61 to 0.93, p=0.008) lower risk for developing cognitive impairment, respectively. A similar pattern of significantly protective association was found at 4-year follow-up. Combined effect analysis showed that participants who attended one type of social engagement had a lower risk of developing cognitive impairment and the protective effect was even larger with those who attended two or three types of social engagement.ConclusionsSocial engagement had a protective effect on cognitive impairment among middle-aged and older adults in China. Given the growing epidemic of dementia and rapid pace of ageing in low-income and middle-income countries, our study shed lights on comprehensive and tailored public health programmes for improving social engagement, to delay cognitive impairment at mid-age and later life.

Background: Depressive symptoms has become an increasingly important public health issue, contributing to disability and disease burden around the world. Higher socioeconomic status (SES) has been found to be associated with lower prevalence of depression, but there are few studies about the older Chinese adults with longterm follow up and rigorous prospective design. Meanwhile, there is little conclusive evidence about the mechanisms through which SES influences the onset of depressive symptoms. Objective: To prospectively examine the association of baseline socioeconomic factors with the risks of developing depressive symptoms during 7-year follow up in older Chinese population, and to study the mechanism by which SES impacts the prevalence of depressive symptoms. Methods: A total of 5677 individuals over 45 years who participated in an ongoing nationally representative prospective cohort study, China Health and Retirement Longitudinal Study, were free from depressive symptoms at baseline, and completed 7-year follow-up were included. Depressive symptoms were assessed using the 10item Center for Epidemiological Studies Depression Scale score. Cox proportional hazards regression models were used to examine the association of SES and the incidence of depressive symptoms in 2011 to 2018. Generalized structural equation model was used to analyze the mediation effects of social support on the relation between SES and depressive symptoms.Results: During the 7-year follow-up, 2398 (42.2%) cases were identified as depressive symptoms. Compared with the lowest level of household income, participants with the highest level of household income had a 20% reduction in risk (95% CI, 0.70-0.92, P < 0.001). Participants who had junior high school or above education had a 41% lower risk of depressive disorders compared with illiterate participants (95% CI, 0.52-0.69, P < 0.001). The relationship between SES and depressive symptoms was partially mediated by the social support, where higherThis is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.