BACKGROUND:To compare the adherence and efficacy between the 0 - 7 - 21-day and the 0 - 1 - 6-month hepatitis B virus (HBV) vaccination schedules among people who use drugs (PWUD) in China. RESEARCH DESIGN AND METHODS:A randomized controlled trial was conducted in 1261 HBV-susceptible PWUD from compulsory isolated detoxification centers (CIDCs) and methadone maintenance treatment (MMT) clinics in Xi'an. A 20 µg per-dose vaccine was used. HBV surface antibody (anti-HBs), surface antigen, and core antibody were tested at months 7, 15, and 22 after the first dose. RESULTS:Third-dose coverage was significantly higher in the 0 - 7 - 21-day group (74.40%) than in the 0 - 1 - 6-month group (51.58%, p < 0.001), mainly driven by participants from CIDCs (77.75% vs. 45.69%). Anti-HBs positive rates at months 7, 15, and 22 among participants who completed all three doses were significantly higher for the 0 - 1 - 6-month schedule (90.71%, 76.82%, and 67.35%) than for the 0 - 7 - 21-day schedule (74.23%, 49.40%, and 40.95%; all p < 0.001). HBV infection incidence was similar between schedules, but significantly different between vaccinees and non-vaccinees (p = 0.018). CONCLUSIONS:The 0 - 7 - 21-day schedule substantially enhances three-dose completion in PWUD, but induces a notably weaker anti-HBs response and persistence. Schedules should be selected based on the management models for PWUD and their individual characteristics. CLINICAL TRIAL REGISTRATION:Chinese Clinical Trial Registry (ChiCTR1900022403).

Varicella is a highly prevalent infectious disease with a similar transmission pathway to coronavirus disease 2019 (COVID-19). In the context of the COVID-19 pandemic, anti-COVID-19 non-pharmaceutical interventions (NPIs) have been implemented to prevent the spread of the infection. This study aims to analyze varicella’s epidemiological characteristics and further investigate the effect of anti-COVID-19 NPIs on varicella in Xi’an, northwestern China. Based on the varicella surveillance data, search engine indices, meteorological factors from 2011 to 2021 in Xi’an, and different levels of emergency response to COVID-19 during the pandemic, we applied Bayesian Structural Time Series models and interrupted time series analysis to predict the counterfactual incidence of varicella and quantify the impact of varying NPIs intensities on varicella. From 2011 to 2021, varicella incidence increased, especially in 2019, with a high incidence of 111.69/100,000. However, there was a sharp decrease of 43.18% in 2020 compared with 2019, and the peak of varicella incidence in 2020 was lower than in previous years from the 21st to the 25th week. In 2021, the seasonality of varicella incidence gradually returned to a seasonal pattern in 2011-2019. The results suggest that anti-COVID-19 NPIs effectively reduce the incidence of varicella, and this reduction has spatiotemporal heterogeneity.

BACKGROUND At the beginning of the COVID-19 pandemic, a cluster outbreak caused by an imported case from Hubei Province was reported in Xi'an City, Shaanxi Province, China. Ten patients from 2 families and 1 hospital were involved in the transmission. MATERIAL AND METHODS We conducted an epidemiological investigation to identify the cluster transmission of COVID-19. The demographic, epidemiological, clinical, laboratory, and cluster characteristics were described and analyzed. RESULTS From January 27 to February 13, 2020, a total of 10 individuals were confirmed to be infected with SARS-CoV-2 by the nucleic acid testing of nasopharyngeal swabs from 2 families and 1 hospital. Among the confirmed cases, 7 had atypical clinical symptoms and 3 were asymptomatic. The median times from onset to diagnosis and to discharge were 3.5 days (range, 1-5 days) and 19.5 days (range, 16-38 days), respectively. There were 4 patients whose exposure dates were 1, 3, 3, and 2 days earlier than the onset dates of their previous-generation cases, respectively. Four prevention and control measures were effectively used to interrupt the disease transmission. CONCLUSIONS SARS-CoV-2 can be easily transmitted within families and in hospitals, and asymptomatic patients could act as a source of disease transmission. The results of this outbreak at the early epidemic stage support the recommendation that individuals with confirmed COVID-19 and all their close contacts should be subjected to medical quarantined observation and nucleic acid screening as early as possible, even if they do not have any symptoms. Meanwhile, people in high-risk areas should improve their protective measures.

目的 描述陕西省COVID-19确诊病例的空间流行病学特征,分析其相关因素,为陕西省新型冠状病毒肺炎的防控工作的开展提供参考依据.方法 收集陕西省COVID-19确诊病例信息及相关社会经济学数据,分析确诊病例的时间及空间分布特征,采用广义线性模型探索人群COVID-19发病与社会经济因素之间的关联.结果 2020年1月23日,陕西省首次报告4例,2月4日新增确诊病例最高达23例,2月19日后再无新增.输入型病例比本地病例更早出现并达到新增高峰,且更早进入归零期.空间分析结果显示,确诊病例数最多的地市为西安市(120例),占总数的48.98％,确诊病例较多的区县为莲湖区、雁塔区、新城区和未央区.与各区县确诊病例数相关的社会经济学因素为教育支出(IRR=0.287,95％ CI:O.134～0.612)、人均生产总值(IRR=1.143,95％ CI:1.049～1.245)及各区县与武汉市的距离(IRR=0.995,95％ CI:0.992～0.998).结论 应针对重点地区和人群在疫情出现早期积极采取相应的措施,及早控制疫情的发展蔓延.

目的 探讨陕西省手足口病疫情的时空演变规律,为优化手足口病的防控策略提供科学依据.方法 陕西省2013-2017年手足口病疫情个案数据来源于中国疾病预防控制信息系统,同期人口数据来源于陕西省统计年鉴,采用R 3.4.1、ArcGIS 10.2和SaTScan 9.2软件进行时空流行病学特征分析.结果 陕西省2013-2017年累计报告手足口病284 225例,年均发病率150.45/10万;历年4-7月病例数占总病例数的70.69％,高发病率区县主要分布在关中地区的中东部区域.重症病例、死亡病例分布与总病例的空间分布基本一致.时空扫描分析显示,全省2013-2017年手足口病存在4个高发热点区域;疫情的一类聚集区固定在以西安市为中心的全省中部和东南部区县(RR=2.25,95％CI:2.18～3.11,P＜0.001),但二类聚集区位置不固定.全省2013-2017.年手足口病的优势流行病原为其他肠道病毒.结论 陕西省手足口病疫情存在显著的时空聚集性特征,近年来病原以其他肠道病毒为主,呈现多病原交替流行;应针对不同时段和地区采取针对性的措施,以有效控制发病.

目的 分析西安市2020年1起中学水痘暴发疫情的流行病学特征和突破病例发病危险因素.方法 对本起疫情开展水痘病例主动搜索和流行病学调查,描述性分析流行病学特征;采用病例对照研究分析水痘突破病例的危险因素.结果 本起中学水痘暴发疫情持续65d,水痘总罹患率为1.84％(49/2 661),其中学生、教职工罹患率分别为2.06％(48/2 328)、0.30％(1/333).高一、高二、高三年级学生罹患率分别为5.17％(42/812),0.66％(5/759)、0.13％(1/757);0、1、2剂次水痘疫苗(VarV)免疫史学生罹患率分别为3.86％(14/363)、1.91％(32/1 679)、1.18％(2/170).在学生中 1 剂次、2剂次 VarV 的疫苗保护率分别为50.52％(95％CI:45.55％-55.48％)、69.43％(95％CI:64.66％-73.82％).学生水痘突破病例罹患率为1.84％(34/1 849).住校、班内有其他病例、接种VarV年限≥9年、学校食堂就餐、仅接种1剂次VarV是突破病例的危险因素[OR(95％CI):3.08(1.12-8.47)、2.86(1.04-7.87)、3.13(1.20-8.18)、4.96(1.51-16.28)、6.79(1.45-31.80)].结论 本起中学水痘暴发主要与未及时发现病例和控制传播以及学生VarV保护水平下降有关;建议儿童入学前完成2剂次VarV接种.

目的 分析手足口病病例可能的感染来源和影响发病的主要因素,为制定手足口病的针对性防控策略提供科学依据.方法 采用随机整群抽样方法,于2019-03/07在全市使用统一的调查问卷开展1:1现场病例对照调查和数据收集.采用广义估计模型和Logistic回归分析方法分析手足口病发病的危险因素及保护因素.结果 累计调查1936人,问卷回收率99.05％(1 936/2 080).统计分析显示儿童年龄、现住址类型、初步诊断、看护人文化、是否多次转诊、洗手与晾晒衣被、通风与消毒是手足口病发病的影响因素,其中,小年龄、首发症状为高热、初步诊断不明确、多次转诊、首发症状到初诊的间隔时间长、EV71感染是手足口病重症病例发生的危险因素.结论 西安市儿童手足口病发病有明显的危险因素,应采取针对性措施积极控制手足口病疫情.

目的 对西安市新型冠状病毒肺炎(简称新冠肺炎,COVID-19)疫情流行特征进行分析,为更好地防控疫情提供参考.方法 采用描述性流行病学方法对疫情应急处置期间病例的现场流行病学调查资料进行分析.结果 截至7月25日全市共报告COVID-19病例145例,含确诊病例120例,无症状感染者25例;湖北输入病例42例,其他省市输入病例8例,本地继发病例84例,感染来源不明确者11例;27起聚集性疫情涉及病例116例;死亡3例.输入病例和本地继发病例分别于1月23日-29日和1月26日-2月4日出现发病高峰,分别为27例和44例;未央区、莲湖区、新城区和雁塔区报告病例数居全市前四位,共占54.48％(79/145);45 ～54岁者占全部病例22.76％(33/145).病例从发病到首诊,发病到隔离,首诊到隔离,发病到确诊,首诊到确诊和隔离到确诊的时间依次为1.33(0.17,3.67)d,3.04(0.59,5.18)d,0.04(0.02,2.00)d,5.50(2.56,9.50)d,3.17(1.56,5.84)d和1.63(1.32,3.35)d.结论 聚集性发病是西安市COVID-19疫情最重要的流行特征.应急响应后西安市医疗系统接诊后的处置和诊断迅速有力,全市今后的防控重心是防止境外病例输入.

目的 了解丽江野鼠鼠疫自然疫源地动物鼠疫流行季节宿主动物及其寄生蚤的群落结构特征,为鼠疫防控提供参考依据.方法 以丽江新发现鼠疫自然疫源地空间范围为调查样区,海拔2 040～3 160 m,选择农耕、居民和机场机坪3种生境进行宿主动物及其寄生蚤调查,运用群落生态学指标对宿主动物及其体表寄生蚤进行群落结构和物种多样性分析.结果 共调查捕获宿主动物1 229只(3目5科7属15种),捕获率为20.66％,农耕区优势种为齐氏姬鼠(52.62％)和大绒鼠(36.23％),居民区优势种为黄胸鼠(37.50％)和褐家鼠(31.25％);坝区大绒鼠(44.39％)相对较多,山区齐氏姬鼠(70.48％)占绝对优势,坝区和山区宿主动物多样性指数分别为1.259和0.928,均匀度分别为0.507和0.403,优势度分别为0.363和0.544,群落相似性指数为0.47.检获宿主动物体表寄生蚤2科5属6种475匹,染蚤率为12.45％,体蚤指数为0.39;宿主动物体表寄生蚤优势种为方叶栉眼蚤(64.21％)和特新蚤指名亚种(24.21％),方叶栉眼蚤和特新蚤指名亚种分别是大绒鼠和齐氏姬鼠寄生蚤优势种,分别占93.48％和68.35％;居民区褐家鼠和黄胸鼠染蚤率较高,分别为25.00％和18.18％;耕作区大绒鼠染蚤率相对较高,为17.42％;山区寄生蚤物种多样性和均匀度较坝区高,而生态优势度较坝区低.结论 动物鼠疫流行季节疫源地宿主动物及其寄生蚤优势种地位突出,宿主动物和媒介蚤类群落生态结构、分布格局和数量变化与鼠疫流行有密切联系,需加强流行季节宿主动物媒介监测,加强流行季节前重点地区预防性灭鼠灭蚤工作,做好疫区防治知识培训和宣传教育.

目的 明确2019年不同水文期X市汉江水源水及其自来水中有机提取物的致突变性强度水平现状、变化趋势以及常规水处理工艺与管网输送对此趋势的影响.方法 应用XAD-2大孔树脂富集汉江流域X城市水源水、出厂水、末梢水中的有机物,经洗脱、浓缩、干燥制得非挥发性有机物(NOCs)干品,运用Ames试验检测并比较各水样中NOCs的致突变性.结果 在0.5～4.0L/皿的测试浓度范围内,枯水期出厂水、末梢水的NOCs对TA98(±S9)的致突变性检测结果为阳性(MR值＞2),在加S9后致突变性降低(MR值降低);其余水样的检测结果均为阴性.平水期出厂水、末梢水的NOCs仅对TA98(-S9)的检测结果为阳性,在加S9后致突变性降低;其余水样的检测结果均为阴性.丰水期时,除汉江出厂水外,其他水样对TA98(±S9)的检测结果均为阴性.但各水文期各水样NOCs对TA100(±S9)的检测结果均为阴性.出现阳性结果时的最低水样量为1.0 L/皿.结论 2019年X市的汉江供水水体(水源水及其自来水)中的有机提取物具有一定的致突变性.Ames试验呈阳性时的水质属于中度污染.致突变性强度依次为枯水期＞平水期＞丰水期.水源水经自来水厂消毒处理后,水中有机物致突变性增强,但经过管网后有所降低.水样中非挥发性有机致突变物的作用类型主要为移码突变型.

目的 调查丽江市古城区野鼠鼠疫疫源地宿主动物携带鼠疫噬菌体情况,并探讨其流行病学意义,为野鼠鼠疫疫源地宿主动物的防制提供科学依据.方法 2017年9月于丽江市古城区5个乡镇共13个野鼠鼠疫疫源地的鼠疫流行自然村采用5 m夹线法进行捕鼠,以鼠疫疫苗株EV76为饲养菌(即鼠疫噬菌体的宿主菌),采用双层平板法分离鼠疫噬菌体,对所分离噬菌体进行噬菌斑观察和电镜下形态鉴定.结果 在丽江古城区5个乡镇共捕鼠766只,其中七河321只,文化镇131只,开南良美48只,大东乡117只,金安乡149只,采集鼠回盲段样本766份,在34份样本中分离34株鼠疫噬菌体,鼠疫噬菌体分离率4.43％;5个乡镇均分离到鼠疫噬菌体,其中七河噬菌体阳性率较高(6.85％).34株鼠疫噬菌体中,29株分离自齐氏姬鼠,2株分离自大绒鼠,3株分别来自灰麝鼩、斯氏家鼠和树鼩.齐氏姬鼠的噬菌体阳性率显著高于其他鼠种,其所分离鼠疫噬菌体的噬斑出现特大(直径2.5～＜3.5 mm)、大(直径1.5～＜2.5 mm)、中(直径0.5～＜1.5mm)及小(直径＜0.5mm)四种噬菌斑.结论 丽江市古城区野鼠鼠疫疫源地宿主动物中携带一定数量的鼠疫噬菌体;因齐氏姬鼠的噬菌体携带率远高于其他鼠种,证明齐氏姬鼠是该疫源地的主要宿主.

Objectives: Hand, foot and mouth disease (HFMD) is a new infectious disease that has attracted much attention at home and abroad, and it spreads widely. In this study, we aimed to explore the interaction between the main pathogens of HFMD through the model of transmission dynamics. Method: The database of HFMD in Xi'an City was established and the main pathogens (EV71, CoxA16, other enteroviruses) were monitored for a long time. In the study, we defined the ascending period of reported cases as Rasc, and the descending period as Rdes, and calculated the regeneration number of the two periods using susceptible–infectious–recovered model. Results: In Xi’an City, Rasc and Rdes of HFMD was 1.39 (95% CI: 1.31 – 1.48) and 0.70 (95% CI: 0.65 – 0.74), respectively. CoxA16 and other enteroviruses interacted with each other and decreased the value of Rasc. However, Rdes of CoxA16 was increased by other enteroviruses directionally. However, during the reported cases decreasing period, interactions only occurred between EV71 and other enteroviruses and between CoxA16 and other enteroviruses. These interactions all decreased Rasc but increased Rdes of affected pathogens. Conclusions: There is interaction among pathogens of HFMD in Xi'an City. The reproduction number of pathogens increased or decreased to a certain extent after interaction, and finally approached 1.

目的 分析西安市手足口病聚集性疫情的流行病学和病原学特征,为防控工作提供科学依据.方法 采用描述性流行病学方法对西安市2014-2019年手足口病聚集性疫情数据进行分析,通过RT-PCR方法进行病原鉴定.采用SPSS 20.0软件进行Mann-Whitney U检验、χ2检验.结果 西安市2014-2019年累计报告手足口病聚集性疫情4246起,涉及病例11280例.聚集性疫情每年主要发生在4～7月(58.10％).雁塔区、长安区和未央区的疫情数位居全市前3位.疫情发生场所以托幼机构为主(87.52％).疫情的肠道病毒阳性检出率为56.99％(1671/2932),其中以Cox A16(23.53％,690/2932)为主.疫情发生报告间隔与疫情持续时间、发病人数呈正相关(r分别为0.727、0.502,P<0.05).结论 西安市手足口病聚集性疫情主要发生在托幼机构,春夏季高发.

目的 调查分析西安市一起新型冠状病毒肺炎(COVID-19)家族聚集性疫情传播特征,为制定防控策略提供科学依据.方法 对COVID-19确诊病例、无症状感染者及密切接触者进行流行病学调查,分析疫情的传播链,采集病例及相关人员的鼻咽拭子标本进行SARS-CoV-2核酸检测.结果 本次疫情累计发现4例普通型、1例危重症型确诊病例和2例无症状感染者,危重症病例最终死亡.首例病例A于2020年1月31日发病,其他病例在首例病例发病后的1～13 d内发病,病例B、C和D、E分别为二、三、四代病例.结论 家族聚集性疫情是COVID-19的防控重点,及早发现传染源,对密切接触者进行筛查隔离,防止传播扩散有重要意义.

[目的]调查分析陕西省W市一起参加葬礼引起的新型冠状病毒肺炎聚集性疫情传播特征,为制定防控策略提供科学依据.[方法]对确诊病例及无症状感染者及其密切接触者进行流行病学调查,分析疫情的传播链,采集病例及相关人员的鼻咽拭子标本进行新型冠状病毒(SARS-CoV-2)核酸检测.[结果]本次疫情累计发现5例普通型、1例重症型确诊病例和1例无症状感染者,罹患率为5.88％(6/102).首例病例A于2020年1月25日发病,其他病例发病日期为首例病例发病后3～13 d,病例B、C、D,病例E、F分别为二至三代病例.疫情由同一时段人员参加葬礼聚会时密切接触而传播,潜伏期中位数为11.5 d.[结论]2019-nCoV传播能力强,应及早发现传染源,做好个人防护,尽量减少人群聚会,控制聚集性疫情的发生.

目的 探讨西安市新型冠状病毒肺炎(COVID-19)疫情的流行规律,为优化疫情防控策略提供科学依据.方法 采用Excel 2007、SPSS 18.0、ArcGIS 10.3软件对COVID-19疫情数据进行描述性流行病学分析;采用内插法计算COVID-19的潜伏期.结果 西安市截至2020年3月6日累计报告COVID-19确诊病例120例、疑似病例738例,报告发病率约为1.20/10万;死亡1例,病死率为0.83％.确诊病例以轻症为主(92.50％),男性发病数(63例)多于女性(57例),41 ～50岁病例数最多(21.97％).发病高峰出现在2020年1月25日和1月31日.高发病地区主要分布在主城区的4个街道办事处(21.67％,26/120).108例出院病例的平均住院时间为16.00(15.58:±:5.45)d.全市累计发生23起聚集性疫情,二代病例的平均续发率为31.73％,其中13起(56.52％)的聚集性疫情发生在家庭内.西安市COVID-19的平均潜伏期为9d.累计报告无症状感染者25例,占SARS-Cov-19感染者的比例为17.24％(25/145).结论 西安市COVID-19疫情整体划分为二个阶段,病例呈现随机的灶状分布,未出现当地大范围传播,需警惕家庭聚集性和无症状感染者传播的风险.

目的 调查2019年西安市X大学第一附属医院住院患者腹泻暴发疫情的致病因子或危险因素,提出针对性防控措施和建议.方法 开展病例搜索和现场流行病学、卫生学调查,采集病例及相关人员、医院水及环境表面等标本,并通过反转录-聚合酶链式反应(RT-PCR)进行病原学检测.结果 调查住院患者、家属陪护、医院职工169人,累计发病22例,总罹患率为13.02％.病例临床表现以腹泻、腹胀、呕吐等为主.病区住院患者罹患率明显高于家属陪护(x2=16.341,P＜0.01);与首发病例共用厕所的住院患者及其家属陪护罹患率明显高于不共用厕所者(x2 =3.907,P＜ 0.05).尚未发现水源性和食源性可疑危险因素.20份病例标本和1份病房拖把表面涂抹标本检测结果为诺如病毒GⅡ型核酸阳性.结论 该起急性胃肠炎暴发疫情属于医院感染事件,由诺如病毒GⅡ型引起.传染源为隐性感染者或病毒携带者,病毒通过病房污染拖把(共同介质)以人-环境-人的模式造成传播,采取针对性措施后疫情得以控制.

OBJECTIVE: To explore the early features of COVID-19 epidemic in Shaanxi Province so as to provide scientific basis for optimizing the prevention strategies and evaluating the effects of interventions METHODS: The epidemic data that were reported through official networks of Shaanxi Province from Dec 31, 2019 to Feb 13, 2020 and the case data from Chinese Information System for Disease Control and Prevention were collected, the population data during the same period were obtained from Shaanxi Statistical Yearbook The descriptive epidemiological analysis was performed by using Excel and ArcGIS software, the transmission dynamics model of COVID-19 was built based on Berkeley Madonna software experiment platform, and the rules of occurrence and progression of the disease were observed RESULTS: By Feb 13, 2020, the accumulative confirmed cases of COVID-19 reached 230 in Shaanxi Province, and the incidence rate was about 0 59 per 100 000 The male cases were more than the female cases, and the patients aged between 40 and 50 years old were dominant The COVID-19 was highly prevalent in Xi\u0027an, Ankang and Hanzhong The SEIAR model showed that the basic regeneration index(R0) of the epidemic in Shaanxi Province was about 2 95, concluding that the beginning of Feb 2020 was the peak period of outbreak of COVID-19 in Shaanxi Province CONCLUSION: The COVID-19 epidemic in Shaanxi province shows a fast spreading trend The theoretical number of confirmed cases that is predicted based on the SEIAR model can provide basis for prevention and control of the COVID-19 epidemic and curb the spread of the epidemic

目的 分析陕西省新型冠状病毒肺炎(coronavirus disease 2019,COVID-19)疫情流行特征,为更好地防控疫情提供参考依据.方法 从陕西省卫生健康委员会官网上收集全省CO-VID-19病例个案资料,采用描述性流行病学方法进行分析.结果 截至2020年3月15日,全省共报告COVID-19病例245例(男131例,女114例),含输入病例116例(有湖北旅居史者97例),本地续发病例114例,无明确接触史者15例;死亡2例.共报告46起聚集性疫情,家庭聚集性疫情占84.78％ (39/46).两次疫情高峰分别出现在1月27日(20例)和1月31日(18例).西安市报告病例占全省48.98％(120/245).40～岁病例最多(60例).病例发病到首诊时间为1.0(0.5,3.0)d,首诊到确诊为4.0(3.0,6.0)d,发病到确诊为6.0(4.0,9.0)d.本地病例发病到确诊时间(7 d)较输入病例(5 d)长;首诊前服药病例发病到确诊时间(9 d)较未服药病例(6 d)长;首诊选择社区医院病例首诊到确诊时间(7 d)较二级(3 d)、三级(4 d)医院病例长.结论 陕西省CO-VID-19疫情分为输入病例为主和本地病例为主两个阶段,家庭聚集性是其重要特征.病例感染来源,首诊前是否服药和首诊医院级别可影响疾病确诊.

Objective:To describe the epidemiological and etiological characteristics of clustered cases of hand, foot, and mouth disease (HFMD) in Xi’an from 2013 to 2018, so as to provide scientific evidences for HFMD prevention and control.Methods:Descriptive epidemiological method was used to analyze the epidemiological characteristics of clustered cases of HFMD in Xi’an from 2013 to 2018.Results:From 2013 to 2018, 4 221 clusters of HFMD were reported, affecting 12 301 individuals. The annual incidence peaks of HFMD clusters occurred during April to July. The top-three districts of the accumulative number of clusters were Yanta, Chang'an and Weiyang. The clusters mainly occurred in child care facilities. The overall positive rate of enteroviruses was 55.37% (1 620/2 926) and coxsackievirus A16 was the predominant type. the time intervals between initial onset and reporting were positively correlated with the duration and case numbers of the clusters (the r values were 0.727 and 0.507, respectively; P<0.05) . Conclusions:The clustered HFMD cases in Xi’an mainly occurred in child care facilities during spring and summer. It is necessary to strengthen the epidemic surveillance, the reporting management, and the sample collection and testing of cases in the high incidence areas, so as to control effectively the clustered cases.