With the comprehensive implementation of prevention and control measures for endemic fluorosis and endemic arsenicosis in China, and in accordance with the World Health Organization (WHO) recommended drinking water standards and the Chinese standards of allowable daily fluoride intake and limit values of arsenic content in drinking water, Chinese residents have entered the era of low-dose fluoride and arsenic exposure. However, there have been few studies focused on the long-term health effects of exposure to low-dose fluoride and arsenic both domestically and internationally. Further more, study on non-target organs of fluoride and arsenic has been neglected. The conclusions are also inconsistent, and there is an urgent need for systematic study to clarify them. Accordingly, this paper proposes to establish a cohort of people exposed to low-dose fluoride and arsenic, systematically carry out study on the long-term health effects and mechanisms of low-dose fluoride and arsenic exposure, and promote China's prevention and control experience to the "the Belt and Road" countries, in order to provide a scientific basis for the formulation of prevention and control strategies and measures for endemic fluorosis and endemic arsenicosis under the new situation in China.

Iodine is an essential micronutrient for human growth and development. It is crucial for neural development in fetuses and newborns in the early postnatal period, including neural migration, glial differentiation, and myelin formation in the central nervous system. Mothers must consume sufficient iodine during pregnancy to maintain fetal growth and development. However, the results of current researches on the potential effects of maternal iodine intake imbalance during pregnancy on offspring iodine nutrition, neurological and physical development are not completely consistant. This article reviews the research in recent years on the effects of maternal iodine intake imbalance during pregnancy on the iodine nutrition and development of offspring, aiming to provide scientific basis for improving offspring development from the perspective of maternal iodine nutrition.

Objective:To construct an entrustable professional activities (EPAs) assessment framework for undergraduate medical students suited to the national conditions in China.Methods:The Delphi method was used to construct an EPAs assessment framework for medical undergraduates. Twenty-one clinical experts across China were invited to participate in two rounds of Delphi consultation.Results:All the 21 experts completed the two rounds of Delphi consultation. The effective questionnaire response rates of the two rounds of consultation were 100.0% (21/21). For the first-round expert consultation, the W values of importance and feasibility scores of EPAs were 0.182 and 0.173 (both P<0.05), respectively. For the second-round expert consultation, the W values of importance and feasibility scores of EPAs were 0.167 and 0.152 (both P<0.05), respectively. According to the second-round Delphi consultation, the importance and feasibility scores of all 14 EPAs indicators were >3.5 points, with the coefficients of variation <0.25 points. We preliminarily established 12 EPAs indicators and 42 key assessment points and determined the expected entrustment levels of each EPA at different stages for medical undergraduates. Conclusion:This study preliminarily constructed an EPAs assessment framework for medical undergraduates, which provides a new evaluation method for the cultivation of medical undergraduates in China.

Over the past decade, remarkable progress has been made in prevention and control of endemic diseases in China through implementation of the 12th and the 13th Five-Year National Plans for Prevention and Control of Endemic Diseases and the Three-Year Action Plan for Special Prevention and Control of Endemic Diseases. Based on the latest monitoring data of endemic diseases and the evaluation results of the control and elimination of endemic diseases of the 13th Five-Year Plan, this paper analyzed current main problems in prevention and control of endemic diseases in China, focusing on implementation of prevention and control measures for iodine deficiency disorders, endemic fluorosis, and endemic arsenicosis, as well as the treatment and management of patients. Accordingly, corresponding countermeasures and suggestions are put forward from three aspects, including prevention and control mechanism, implementation of prevention and control measures, and scientific research, so as to provide scientific basis for the country and various regions to consolidate the achievements of prevention and control of endemic diseases and accurately implement the prevention and control measures of endemic diseases.

Objective:To analyze the global epidemic data of Corona virus disease 2019 (COVID-19) and the prevention and control measures, learn about the epidemic characteristics, development trend and the main factors affecting the prevention and control effect, and provide reference for scientific prevention and control of COVID-19.Methods:The data of COVID-19 mainly came from the WHO website and the websites of the United States, European and other Centers for Disease Control and Prevention (the statistical time was from the beginning of the epidemic in each country to March 31, 2022). The epidemiological characteristics and trends in the world and major countries were analyzed, and the main factors affecting the prevention and control of the epidemic were studied. SPSS19.0 software was used to collate data and statistical analysis.Results:The worldwide cumulative confirmed cases of COVID-19 reached 1 million on April 2, 2020, 10 million cases on June 28, 2020, 100 million cases on January 25, 2021, 200 million cases on August 3, 2021, 300 million cases on January 6, 2022, 400 million cases on February 8, 2022, 489 million cases on March 31, 2022. From January 2020 to March 31, 2022, the interval between each additional 100 million cases was gradually shortened (about 360 days from the beginning of the epidemic to the increase to 100 million, the average time to increase from 100 million to 200 million, from 200 million to 300 million was 170 days, and the number of confirmed cases increased from 300 million to 400 million was only 33 days), the epidemic had accelerated. The worldwide cumulative number of death case was 100 000 on April 9, 2020, 1 million on September 19, 2020, 5 million on October 31, 2021, and 6.14 million on March 31, 2022. From January to October 2021, the average time interval for an increase of 1 million deaths was 97 days. After October, the growth rate decreased, averaging 121 days. At the end of 2021, affected by the Omicron mutation, the number of infected people worldwide increased sharply. By March 31, 2022, the cumulative number of confirmed cases in all continents was Europe (181 million), Asia (141 million), North America (94.67 million), South America (56.09 million), Africa (11.55 million) and Oceania (5.58 million) from high to low. The cumulative deaths from high to low was Europe (1.77 million), North America (1.42 million), Asia (1.41 million), South America (1.28 million), Africa (0.25 million) and Oceania (8 900). The top 5 countries with cumulative confirmed cases of COVID-19 were the United States (80.14 million), India (43.03 million), Brazil (29.98 million), France (25.82 million) and the United Kingdom (21.28 million). The top five countries with accumulated deaths were the United States (980 000), Brazil (660 000), India (520 000), the United Kingdom (160 000) and France (140 000).Conclusions:COVID-19 is a global public health emergency. The epidemic has spread worldwide with strong infectivity, rapid transmission and great harm. It is suggested to focus on the prevention and control of key links, strengthen the early warning mechanism, continue to take scientific public health prevention and control measures such as vaccination, reduce severe case and death and deal with an ongoing challenge.

Objective:To study the effect of iodine excess on antioxidant capacity and blood lipid in adult.Methods:A survey was conducted in areas with different iodine nutrition levels in Shandong and Shanxi provinces to collect fasting morning urine and venous blood samples of adults. Urinary iodine, serum levels of superoxide dismutase(SOD), malondialdehyde (MDA), total cholesterol (TCHO), triglyceride (TG), apolipoprotein A1 (apoA1) and apolipoprotein B (apoB), high density lipoprotein cholesterol (HDL-C) and low density lipoprotein cholesterol (LDL-C) were determined. According to the median urinary iodine of the population in the investigated village, they were divided into appropriate iodine group (100-299 μg/L) and iodine excess group (≥300 μg/L) . Multiple linear regression was used to analyze the effects of iodine nutrition and other factors on oxidative stress indexes and blood lipids. Partial correlation analysis was used to analyze the relationship between iodine nutrition and oxidative stress indexes and blood lipids.Results:A total of 1 049 subjects were included, including 471 in the appropriate iodine group and 578 in the iodine excess group. The median (quartile) urinary iodine of the appropriate iodine group and the iodine excess group was 228.70 (157.02, 341.49) and 558.73 (298.06, 985.06) μg/L, respectively. The serum SOD level of the appropriate iodine group and the iodine excess group was 12.60 (10.83, 14.10) and 11.29 (9.18, 13.10) U/ml, respectively, and the difference between the groups was statistically significant ( U = 92 697.50, P < 0.001). There were statistically significant differences in serum TG, HDL-C and apoB levels between the appropriate iodine group and the iodine excess group ( U = 108 879.50, 96 613.50, 99 050.50, P < 0.05). The results of multiple linear regression showed that after excluding age, gender and body mass index (BMI), there was a negative correlation between iodine nutrition and serum SOD and HDL-C levels [standard regression coefficient ( β) = - 0.196, - 0.294, P < 0.001]. Partial correlation analysis showed that there was a negative correlation between iodine nutrition and serum SOD and HDL-C levels [correlation coefficient ( r) = - 0.16, - 0.09, P < 0.05]. Conclusion:Excessive iodine intake affects oxidative stress and lipid metabolism in human body.

Since the 18th National Congress of the Communist Party of China (CPC), the CPC Central Committee and the State Council have paid great attention to the prevention and control of endemic diseases. Through the implementation of the prevention and control measures of endemic diseases, especially the implementation of the "Six Major Actions" to tackle key problems in "three years' project", all kinds of diseases have met the relevant requirements. The prevention and control of endemic diseases in China has achieved remarkable results and made historic achievements. However, risk challenges remain. At present, there are still some problems in the management and treatment of patients with iodine deficiency disorders, water-borne iodine excess goiter, drinking water-borne endemic fluorosis and drinking tea-borne endemic fluorosis in China, which need to be solved by strengthening the prevention and control efforts.

Objective:To observe the epidemiological characteristics and transmission chain of COVID-19 in Harbin, and to provide epidemiological evidence for improving the COVID-19 preventive measures and optimizing prevention and control strategies.Methods:The epidemic situation of COVID-19 in Harbin in January 2021 was analyzed by using the Infectious Disease Report Information Management System and the Public Health Emergency Management Information System of the China Disease Prevention and Control Information System, the epidemic situation information publicly released by the Heilongjiang Provincial Health Commission, and the epidemiological report of Heilongjiang Province Certer for Disease Control and Prevention and Harbin Center for Disease Control and Prevention. The main transmission chains were sorted out through combination of epidemiological field investigation, serological testing, gene sequencing, big data and other means.Results:From January 12 to February 4, 2021, 295 cases of COVID-19 infection (including confirmed cases and asymptomatic infections) were reported in Harbin, which affected 6 districts of Harbin and were concentrated in 41 of the 274 townships in the city. The sex ratio of male to female was 1.00∶1.12 (139∶156); the age ranged from 1 to 86 years old, and the median age was 45 years old. The proportion of confirmed cases and asymptomatic infection was 1.00 ∶ 1.02 (146 ∶ 149), and there was a significant difference in the distribution of different ages between them ( P = 0.042). The cases were mainly found through the health screening of the centralized isolation personnel (178 cases, 60.3%). Other detection methods included active screening (87 cases, 29.5%), screening of the home isolation personnel (26 cases, 8.8%), and medical treatment in medical institutions (4 cases, 1.4%). The main transmission chain of the outbreak was the case associated with a food processing enterprise, with a total of 259 cases, accounting for 87.8% of the total cases. The gene sequencing results showed that the case sequence was homologous with that of Wangkui County, Suihua City, Heilongjiang Province. Conclusions:A food processing enterprise is involved in the main transmission chain, which indicates that the epidemic prevention and control measures needs to be further optimized. Specifically, the supervision and management of food processing enterprises, cold chain storage companies and other enterprises should be strengthened. High attention should be paid to the hidden dangers of COVID-19 in large and medium sized enterprises with hermetic space in Harbin.

Objective:To evaluate the intelligence, movement and physical development of 2-month-old infants, and to explore the influencing factors of early infant development.Methods:A total of 203 infants aged 42 days who underwent physical examination in the Department of Neonatology of the Fourth Affiliated Hospital of Harbin Medical University from May to December 2021 were selected as subjects. At the age of 2 months, 184 infants were followed up for their intelligence, movement and physical development. The intelligence and movement development of infants were evaluated with the intelligence development scale. Their body length, weight, and head circumference were measured, and physical development was assessed by Z-score method. Logistic regression was used to analyze the influencing factors of intelligence, movement and physical development of 2-month-old infants.Results:The median mental developmental index (MDI) of 184 2-month-old infants was 101; the median psychomotor developmental index (PDI) was 89; the body length was (59.3 ± 2.0) cm, the body weight was (5.8 ± 0.6) kg, and the head circumference was (38.9 ± 1.1) cm. Multiple logistic regression analysis showed that the influencing factors of MDI were maternal delivery age and infant gestational age [odds ratio ( OR) = 0.849, 0.463, P < 0.05]; the influencing factors of PDI were maternal prenatal education and average sleep time per night during pregnancy ( OR = 0.512, 0.666, P < 0.05); the influencing factor of body mass index (BMI) was maternal iodine supplements during pregnancy ( OR = 2.858, P = 0.018); the influencing factor of length-for-age Z-score (LAZ) was maternal prenatal education during pregnancy ( OR = 0.265, P = 0.026); the influencing factors of weight-for-age Z-score (WAZ) included maternal average sleep time per night, the frequency of sleeping time exceeding 12 am and the average weekly exercise duration during pregnancy ( OR = 0.277, 1.106, 0.990, P < 0.05). Conclusion:Maternal delivery age, prenatal education, sleep duration, intake of iodine supplements, exercise duration during pregnancy, and infant gestational age are factors affecting the intelligence, movement and physical development of 2-month-old infants, which should be paid attention to and measures should be taken to improve the population quality.

Objective:To analyze the epidemic characteristics of Cornona virus disease 2019 (COVID-19) in Wangkui County, Heilongjiang Province, and to provide a reference for optimizing epidemic prevention and control strategies.Methods:The epidemic characteristics of COVID-19 in Wangkui County, Heilongjiang Province in January 2021 were analyzed by applying the national infectious disease report system and information management system of Heilongjiang Provincial Center for Disease Control and Prevention, the public health emergency report management information system, the epidemiological investigation report of the Heilongjiang Provincial Center for Disease Control and Prevention and Suihua Municipal Certer for Disease Control and Prevention, and the epidemic information publicly released by the Health Commission of Heilongjiang Province.Results:From January 9 to February 5, 2021, 804 cases infected with Cornona virus were reported in Wangkui County, with an infection rate of 280.29/100 000. The epidemic affected 20 districts and counties in 6 cities, including Suihua, Harbin, Mudanjiang, Qiqihar, Yichun and Daqing. The sex ratio of male to female was 1.08 ∶ 1.00 (418 ∶ 386), the age ranged from 3 months to 93 years old, and the median age was 50 years old. The proportion of confirmed cases and asymptomatic infection was 1.23 ∶ 1.00 (444 ∶ 360), there were significant differences in gender, age and occupation between them ( P < 0.05). There were 314 places where the aggregation epidemic occurred, with family aggregation as the main way (300 households, 95.54%). The places with the highert average number of cases were banquets (25.75 cases/place) and grocery stores/chess and card rooms (16.00 cases/place). Conclusions:In January 2021, the epidemic of COVID-19 in Wangkui County is a typical outbreak in rural areas of North China. The main reasons for the rapid spread of the epidemic are a large number of gathering activities, frequent contact of personnel in confined spaces and other factors.