[Typical case analysis of COVID-19 cluster epidemic in Shaanxi, 2020].

Objective: By analyzed the transmission patterns of 4 out of the 51 COVID-19 cluster cases in Shaanxi province to provide evidences for the COVID-19 control and prevention. Methods: The epidemiological data of RT-PCR test-confirmed COVID-19 cases were collected. Transmission chain was drawn and the transmission process was analyzed. Results: Cluster case 1 contained 13 cases and was caused by a family of 5 who traveled by car to Wuhan and returned to Shaanxi. Cluster case 2 had 5cases and caused by initial patient who participated family get-together right after back from Wuhan while under incubation period. Cluster case 3 contained 10 cases and could be defined as nosocomial infection. Cluster case 4 contained 4 cases and occurred in work place. Conclusion: Higher contact frequency and smaller places were more likely to cause a small-scale COVID-19 cluster outbreak, with potential longer incubation period. COVID-19 control strategies should turn the attention to infection prevention and control in crowded places, management of enterprise resumption and prevention of nosocomial infection.

[Analysis of transmission characteristics of COVID-19 in Shaanxi Province].

A total of 245 cases of COVID-19 in Shaanxi Province reported in the China information system for disease control and prevention as of February 24, 2020 were selected as the research objects, the cases are divided into imported cases (116 cases, 47.3%) and local cases (129 cases, 52.7%), their basic characteristics, time distribution, transmission mode, intergenerational interval and latent period transmission are analyzed. The age of local cases [(51.74±15.67) years old], female patients (69 cases, 53.5%), housework and retired staff (40 cases, 31.0%), and patients isolated at the time of onset (50 cases, 38.8%) were higher than imported cases, respectively[(40.66±15.41) years old, (45 cases, 38.8%), (21 cases, 18.1%), (17 cases, 14.6%)] (P values were < 0.05); The infection rate was 0.8% (31/3 666) in close contacts with local cases, which was lower than imported cases 2.0% (69/3 435) (P<0.001); The main source of infection in local cases was relatives (70 cases, 54.3%), and the main way of infection was living together and party (90 cases, 69.8%); the proportion of latent period transmission in our province was 15.5% (20 cases), and the interval between the second-generation case and the source of infection was about 4 days, and the interval between generations was about 6 days. In summary, the main way of infection of local cases in Shaanxi Province was living together and party, there were a certain proportion of latent period transmission cases at present, it's suggested that the investigation of close contacts should be started 4 days or earlier before the onset of the case.

[Epidemiological characteristics of COVID-19 in Shaanxi province].

Objective: To understand the incidence trend and epidemiological characteristics of COVID-19 in Shaanxi province. Methods: The incidence data of COVID-19 reported in Shaanxi as of 22 February, 2020 were collected for an epidemiological descriptive analysis. Results: A total of 245 confirmed cases of COVID-19 were reported in Shaanxi. Most cases were mild (87.76%). As time passed, the areas where confirmed cases were reported continued to increase. The case number in Xi'an was highest, accounting for nearly half of the total reported cases in the province. The epidemic pattern in Shaanxi had gradually shifted from imported case pattern to local case pattern, and the transmission of local cases was mainly based on family cluster transmission. The confirmed cases from different sources had caused the secondary transmission in Shaanxi. After February 7, the number of reported cases began to fluctuate and decrease stably, indicating a decrease-to-zero period. Conclusions: At present, the overall epidemic of COVID-19 in Shaanxi has gradually been mitigated. However, considering the approaching of return to work and study and the increasing of imported cases from other countries, the prevention and control of COVIS-19 in Shaanxi will face new challenges.

[Dynamics and epidemiological characteristics of hand, foot and mouth disease in Shaanxi province, 2009-2018].

Objective: To understand the dynamics and epidemiological characteristics of hand, foot and mouth disease (HFMD) in Shaanxi province during 2009-2018 and provide evidence for prevention and control of HFMD. Methods: Information on HFMD was collected from the Chinese Disease Prevention and Control Information System in Shaanxi Province during 2009-2018 and was analyzed by descriptive, dynamic geometric series averaging and circular distribution methods. Results: The annual average incidence rate of HFMD was 140.04/100 000 in Shaanxi province during 2009-2018. The highest incidence rates were seen in age groups as 1-year olds (3 494.24/100 000), 2-year olds (2 734.79/100 000) and 3-year olds (2 608.58/100 000). The highest reported mortality rates appeared in: 1-year olds as 1.42/100 000, 2-year olds as 0.77/100 000) and 0-year olds (0.53/100 000). The incidence rate increased most rapidly in the 1-year olds and the 0-year olds groups. The top three incidence rates were reported in Xi'an (251.34/100 000), Weinan (161.21/100 000) and Xianyang (123.73/100 000) cities in Guanzhong area of Shaanxi province. In the whole province, incidence rate was on the rise, and the average increases of incidence rates were all greater than zero in these cities. The proportion of severe cases in most cities somehow declined. Results from the circular distribution method estimated that the peak incidence would appear in April 10-11 each year, and the high incidence season was from April to July. In 2018, the composition of enterviruses (EV) 71 was 26.47% (1 303/4 922). In 2014 to 2018, the proportion of Coxsackie virus A16 (Cox A16) was between 20.06%(753/3 753) and 23.08% (855/3 705). The proportions of other EVs increased from 6.09% (14/230) to 51.91% (2 555/4 922) during 2009-2018. Conclusions: The overall incidence rate of HFMD was increasing, with high risk population appeared in children under 3 year olds, in Shaanxi province during 2009-2018. However, both mortality and fatality rates were declining, with severe cases also showing a downward trend in most of the areas. Composition of pathogens was changing over time.