入境人员集中隔离点新型冠状病毒核酸检测阳性病例特征分析

目的 了解浙江省湖州市某入境人员集中隔离点2021年12月18日-2022年1月12日新型冠状病毒(新冠病毒)核酸阳性病例特征,为新型冠状病毒肺炎(新冠肺炎)境外输入疫情防控提供依据.方法 收集该入境人员集中隔离点2021年12月18日-2022年1月12日境外输入新冠病毒核酸阳性病例的基本信息、核酸检测和流行病学调查...     

新型冠状病毒肺炎疫情期间乳腺癌患者优化管理

目的制定新型冠状病毒肺炎疫情期间乳腺癌的管理措施并评估治疗的安全性。方法围绕以下方面优化管理措施:制定疫情期间的入院治疗总体标准,严格疫情期间病区管理严格要求,强化工作人员管理,加强住院患者及居家患者管理。结果 2020年2月1日至2020年2月29日,我科累计为3132人次乳腺癌患者提供诊疗服务,所有患者均未出现确诊或疑似新冠肺炎,仅1例出现Ⅳ度骨髓抑制,给予隔离、紫外线消毒、短效升白、预防感染等对症处理后好转,未发生感染。结论通过制定疫情期间乳腺癌的管理措施,既满足了患者的治疗需求,又保障了患者的治疗安全,大大降低感染风险,提高了突发公共卫生事件应对能力。     

新型冠状病毒Omicron变异株引发天津市家庭聚集性疫情的传播特征及影响因素

目的 了解新型冠状（新冠）病毒Omicron变异株引发天津市家庭聚集性疫情的传播特征及影响因素。方法 采用现场流行病学的方法对新冠病毒肺炎病例进行流行病学调查,对流行病学信息进行描述性分析。结果 本次疫情天津市共报告430名病例,409名符合纳入标准,70.90%（290/409）发生家庭聚集。家庭续发率为33.64%,12~17岁组首发病例家庭续发率（13.79%）明显低于18~49岁组（36.48%）,OR值（95%CI）为0.378（0.170~0.840）。影响家庭聚集发生的多因素logistic回归分析结果显示,首发病例在封/管控区和居家隔离发现较集中隔离发现的OR值（95%CI）分别为2.951（1.322~6.586）和2.287（1.164~4.495）,首发病例出现咽部不适较未出现咽部不适的OR值（95%CI）为3.003（1.576~5.720）;家庭内全部完成全程新冠病毒疫苗接种较未全部完成全程新冠病毒疫苗接种的OR值（95%CI）为0.268（0.132~0.552）。结论 本次新冠病毒Omicron变异株引发家庭聚集性疫情的风险较高,首发病例在封/管控区和居家隔离发现以及首发病例出现咽部不适是发生家庭聚集的危险因素;家庭内完成全程疫苗接种是发生新冠病毒肺炎家庭聚集的保护因素。     

新型冠状病毒疫苗接种对成都市境外输入病例流行病学及临床特征的影响分析

目的 分析新型冠状病毒（新冠病毒）疫苗接种对成都市境外输入病例流行病学及临床特征的影响,为新型冠状病毒肺炎疫情防控提供参考依据。方法 截至2021年4月15日,经成都市入境的新冠病毒感染病例,根据新冠病毒疫苗接种史被分为疫苗接种组和疫苗未接种组。回顾性收集和分析病例的流行病学及临床特征资料。实验室检测项目包括新冠病毒核酸检测、临床指标、血清抗体和淋巴细胞检测。采用WPS 2019软件整理数据,采用R 4.0.3软件进行统计学分析。结果 75例新冠病毒感染病例包括疫苗接种组20例（出现临床症状4例）和疫苗未接种组55例（出现临床症状16例）。疫苗接种组的首针接种时间分布为2020年7-11月,其中接种2剂次疫苗采用一次性接种方式有10例,采取2次间隔接种方式有10例,2次接种间隔14~57 d,完成疫苗接种与发病时间间隔87~224 d。两组病例的分类和临床分型的差异有统计学意义（P<0.05）,其中,疫苗接种组病例分类为无症状感染者的比例较高（40.00%,8/20）,而疫苗未接种组的临床分型以普通型的比例较高（76.36%,42/55）。两组病例的新冠病毒核酸检测2个靶标（ORF1ab和N基因）Ct值、淋巴细胞亚型、降钙素原及C反应蛋白的差异无统计学意义（P>0.05）,疫苗接种组的血清淀粉样蛋白A水平低于疫苗未接种组（P<0.05）,但新冠病毒血清抗体IgM、IgG及总抗体水平均明显高于疫苗未接种组（P<0.05）。结论 新冠病毒疫苗接种后,仍存在感染的风险,但新冠病毒侵入人体后,体内可迅速产生特异性IgM和IgG抗体,对感染者产生一定保护作用,已接种新冠病毒疫苗的病例分类以无症状感染者为主。     

我国坚持新冠肺炎疫情防控“动态清零”不动摇的原因与成效

全球新型冠状病毒肺炎（简称“新冠肺炎”）病例累计>6亿,死亡人数>600万,病死率为1.24%;香港第5波疫情有1/6的人感染,每万人死亡15人。以香港第5波疫情Omicron变异株1/6的人感染、0.76%死亡率和每年1波疫情来推算,中国实施“动态清零”3年就避免了 6 990万人的感染和626万人的死亡。随着病毒传染性增强及变异的加速,已观察不到新冠肺炎变异株超长潜伏期。我国对本土局部暴发疫情后的物理围堵隔离措施更为成熟,社会面“动态清零”更快、需时更短,维护了人民的健康和生命安全。根据Delta株传播率,推测新冠肺炎原始株潜伏期分别为≤4 d、≤7 d及≥8 d的构成情况,根据江苏省扬州市疫情部分病例和北京市小金阁服装店关联传播链疫情病例,统计Delta变异株和Omicron变异株潜伏期构成情况,分析对2022年7月广西壮族自治区北海市和崇左市Omicron变异株疫情处置中社会面“清零”的方法与效果。     

深圳市一起新型冠状病毒Omicron BF.7变异株暴发疫情的流行病学特征

目的分析深圳市一起广东省外输入的新型冠状病毒(新冠病毒)Omicron BF.7变异株所致暴发疫情的流行病学特征, 梳理和分析其传播链条和传播特征。方法采用现场流行病学方法对病例进行调查, 整理新冠病毒感染者活动轨迹、分析代际关系等, 对新冠病毒核酸阳性标本进行基因测序分析。结果 2022年10月8-23日, 深圳市共报告196例新冠病毒感染者, 均存在流行病学关联。男、女性分别为100和96例, 年龄M(Q1, Q3)为33(25, 46)岁。本起疫情由在广东省外旅游返回深圳市的新冠病毒感染者(首发病例)引起, 4条传播链分别为首发病例现住址相关感染8例、7日晚社会面活动相关感染65例、8日写字楼工作场所相关感染累计48例、在工作场所附近的写字楼相关感染74例。本起疫情潜伏期M(Q1, Q3)为1.44(1.11, 2.17)d。室内暴露的潜伏期短于室外暴露的潜伏期, M(Q1, Q3)分别为1.38(1.06, 1.84)和1.95(1.22, 2.99)d, 差异有统计学意义(Waldχ2=10.27, P=0.001)。随着代际的增加, 基因位点突变个数及突变比例增加。在同一传...     

内蒙古某口岸城市新冠感染疫情流行病学特征分析

目的 分析内蒙古满洲里市新冠感染疫情流行病学特征，为口岸城市疫情防控提供参考依据。方法 收集整理2021年11月28日—12月17日传染病报告信息系统满洲里市新冠感染病例信息和流行病学调查报告，采用Excel 2003和SPSS 19.0软件分析流行病学特征和疫情特点。结果 2021年11月28日—12月17日满洲里市累计报告新冠感染病例548例，男女性别比1.03∶1,31～60岁病例占51.6%,职业以家务及待业、学生、工人为主，临床严重程度主要为轻型(46.5%)和普通型(47.6%);早期病例临床症状主要为咳嗽、咽痛、流涕、发热等流感样症状，具有一定隐匿性；病例的疫苗接种比例较高(90.7%),未接种疫苗病例重型、危重型比例高于接种疫苗病例。结论 2021年11月28日—12月17日的满洲里市疫情为一起新的境外输入来源引起的口岸城市疫情，属于Delta变异株，具有场所、家庭、学校聚集特点。疫苗接种可有效降低Delta变异株所致新冠感染患者临床严重程度。     

儿童和青少年新型冠状病毒感染的研究进展

随着成年人大规模接种新型冠状病毒(新冠病毒)疫苗, 儿童和青少年群体由于较低疫苗覆盖率和较高接触度, 逐渐成为新冠病毒感染的脆弱人群, 有必要总结儿童和青少年群体新冠病毒感染特征、新冠病毒疫苗对于变异株的免疫效果。本文检索现有文献, 对儿童和青少年新冠病毒感染的研究进展进行综述, 分析儿童和青少年对于新冠病毒的易感性、感染者的传播力和疾病预后以及免疫应答和新冠病毒疫苗的进展等关键特征, 为新冠病毒肺炎疫情防控提供参考依据。     

新型冠状病毒肺炎疫情多次暴发的动力学机制分析

目的 新型冠状病毒肺炎（新冠肺炎）自暴发以来,世界各国疫情形势、非药物防控措施、疫情下的民众行为模式及疫苗接种等差异巨大。我国疫情也在经历较长时间无本土病例后,由于境外输入等因素引起局部疫情暴发,给疫情防控带来巨大挑战。深入探讨疫情多次暴发的机制和差异性是极为必要的。方法 本研究基于SEIR传染病动力学模型,构建新颖的演化方程来融合干预措施和疫苗接种以及民众行为改变的动态过程。发展方法计算最优的干预强度和疫苗接种速率使得易感人群规模低于其阈值,从而避免疫情的二次暴发。结果 强干预或超强干预措施过早地解除,一个弱的诱因会不同程度地导致新冠肺炎疫情的再次暴发,而且早期控制措施越强,解除后二次暴发的程度越大;民众个体行为变化对疫情的敏感性程度以及防控措施的加强与解除是诱导疫情多次暴发的关键因素;最优的早期干预措施和及时优化接种疫苗不仅能够避免后期疫情的多次暴发,更能有效地降低第一波疫情的峰值并推迟其到来的时间。结论 本研究揭示了干预措施的强弱与解除、民众行为对疫情的响应切换、疫苗接种率和时效性、外界诱因和新冠病毒传播强度等因素诱导新冠肺炎疫情的多次暴发。     

新加坡新型冠状病毒疫苗免疫接种策略研究

截至2021年12月31日,新加坡累计报告已有4 758 601人完成至少一剂次新型冠状（新冠）病毒疫苗接种,4 714 655人完成两剂次新冠病毒疫苗接种,2 207 341人完成新冠病毒疫苗加强针接种。本研究通过深入分析新加坡新冠病毒疫苗接种现状,解读新加坡国家疫苗接种计划内容,系统梳理新加坡新冠病毒疫苗上门接种、...     

COVID-19 Incidence and hospitalization during the delta surge were inversely related to vaccination coverage among the most populous U.S. Counties

ObjectiveWe tested whether COVID-19 incidence and hospitalization rates during the Delta surge were inversely related to vaccination coverage among the 112 most populous counties in the United States, comprising 44 percent of the country's total population.MethodsWe measured vaccination coverage as the percent of the county population fully vaccinated as of July 15, 2021. We measured COVID-19 incidence as the number of confirmed cases per 100,000 population during the 14-day period ending August 12, 2021 and hospitalization rates as the number of confirmed COVID-19 admissions per 100,000 population during the same 14-day period.ResultsIn log-linear regression models, a 10-percentage-point increase in vaccination coverage was associated with a 28.3% decrease in COVID-19 incidence (95% confidence interval, 16.8 - 39.7%), a 44.9 percent decrease in the rate of COVID-19 hospitalization (95% CI, 28.8 - 61.0%), and a 16.6% decrease in COVID-19 hospitalizations per 100 cases (95% CI, 8.4 - 24.8%). Inclusion of demographic covariables, as well as county-specific diabetes prevalence, did not weaken the observed inverse relationship with vaccination coverage. A significant inverse relationship between vaccination coverage and COVID-19 deaths per 100,000 during August 20 – September 16 was also observed. The cumulative incidence of COVID-19 through June 30, 2021, a potential indicator of acquired immunity due to past infection, had no significant relation to subsequent case incidence or hospitalization rates in August.ConclusionHigher vaccination coverage was associated not only with significantly lower COVID-19 incidence during the Delta surge, but also significantly less severe cases of the disease.Public Interest SummaryWe tested whether COVID-19 incidence and hospitalization rates during the Delta variant-related surge were inversely related to vaccination coverage among the 112 most populous counties in the United States, together comprising 44 percent of the country's total population. A 10-percentage-point increase in vaccination coverage was associated with a 28.3% decrease in COVID-19 incidence, a 44.9 percent decrease in the rate of COVID-19 hospitalization, and a 16.6% decrease in COVID-19 hospitalizations per 100 cases. Inclusion of demographic covariables, as well as county-specific diabetes prevalence, did not weaken the observed inverse relationship with vaccination coverage. A significant inverse relationship between vaccination coverage and COVID-19 deaths per 100,000 during August 20 – September 16 was also observed. Higher vaccination coverage was associated not only with significantly lower COVID-19 incidence during the Delta surge, but also significantly less severe cases of the disease.     

基于SVEPIUHDR传染病动力学模型的新型冠状病毒肺炎疫情趋势分析

目的 对美国和英国新型冠状病毒肺炎（COVID-19）疫情的发展趋势进行模型拟合和预测,对疫苗接种的效果进行初步分析。方法 在SEIR模型基础上,增加症状前感染者、隔离措施及疫苗接种等要素,建立SVEPIUHDR模型。利用公开发布的数据建模,分别将美国2020年11月6日至2021年1月31日和英国2020年11月23日至2021年1月31日的数据进行拟合,2021年2月1日至4月1日的疫情数据评估预测效果,使用R 4.0.3软件进行分析,并预测在疫苗不同接种率下每日新增病例数的变化。结果 SVEPIUHDR模型对美国和英国的累计确诊病例数的拟合及预测平均偏差均<5%。按计划接种疫苗后,预计美国2021年4月COVID-19累计确诊人数达31 864 970人,若未接种疫苗,累积确诊人数达35 317 082人,相差345余万人。英国按计划接种疫苗后预计4月初累积确诊人数达4 195 538人,若未接种疫苗情况下累积确诊人数达4 268 786人,相差7万余人。结论 SVEPIUHDR模型对美、英两国COVID-19疫情的预测效果较好。     

Vaccination willingness,vaccine hesitancy,and estimated coverage at the first round of COVID-19 vaccination in China: A national cross-sectional study

BackgroundVaccination against coronavirus disease 2019 (COVID-19) has become an important public health solution. To date, there has been a lack of data on COVID-19 vaccination willingness, vaccine hesitancy, and vaccination coverage in China since the vaccine has become available.MethodsWe designed and implemented a cross-sectional, population-based online survey to evaluate the willingness, hesitancy, and coverage of the COVID-19 vaccine among the Chinese population. 8742 valid samples were recruited and classified as the vaccine-priority group (n = 3902; 44.6%) and the non-priority group (n = 4840; 55.4%).ResultsThe proportion of people’s trust in the vaccine, delivery system, and government were 69.0%, 78.0% and 81.3%, respectively. 67.1% of the participants were reportedly willing to accept the COVID-19 vaccination, while 9.0% refused it. 834 (35.5%) reported vaccine hesitancy, including acceptors with doubts (48.8%), refusers (39.4%), and delayers (11.8%). The current coverage was 34.4%, far from reaching the requirements of herd immunity. The predicted rate of COVID-19 vaccination was 64.9%, 68.9% and 81.1% based on the rates of vaccine hesitancy, willingness, and refusal, respectively.ConclusionsThe COVID-19 vaccine rate is far from reaching the requirements of herd immunity, which will require more flexible and comprehensive efforts to improve the population’s confidence and willingness to vaccinate. It should be highlighted that vaccination alone is insufficient to stop the pandemic; further efforts are needed not only to increase vaccination coverage but also to maintain non-specific prevention strategies.     

A Recursive Model of the Spread of COVID-19: Modelling Study

BackgroundThe major medical and social challenge of the 21st century is COVID-19, caused by the novel coronavirus SARS-CoV-2. Critical issues include the rate at which the coronavirus spreads and the effect of quarantine measures and population vaccination on this rate. Knowledge of the laws of the spread of COVID-19 will enable assessment of the effectiveness and reasonableness of the quarantine measures used, as well as determination of the necessary level of vaccination needed to overcome this crisis.ObjectiveThis study aims to establish the laws of the spread of COVID-19 and to use them to develop a mathematical model to predict changes in the number of active cases over time, possible human losses, and the rate of recovery of patients, to make informed decisions about the number of necessary beds in hospitals, the introduction and type of quarantine measures, and the required threshold of vaccination of the population.MethodsThis study analyzed the onset of COVID-19 spread in countries such as China, Italy, Spain, the United States, the United Kingdom, Japan, France, and Germany based on publicly available statistical data. The change in the number of COVID-19 cases, deaths, and recovered persons over time was examined, considering the possible introduction of quarantine measures and isolation of infected people in these countries. Based on the data, the virus transmissibility and the average duration of the disease at different stages were evaluated, and a model based on the principle of recursion was developed. Its key features are the separation of active (nonisolated) infected persons into a distinct category and the prediction of their number based on the average duration of the disease in the inactive phase and the concentration of these persons in the population in the preceding days.ResultsSpecific values for SARS-CoV-2 transmissibility and COVID-19 duration were estimated for different countries. In China, the viral transmissibility was 3.12 before quarantine measures were implemented and 0.36 after these measures were lifted. For the other countries, the viral transmissibility was 2.28-2.76 initially, and it then decreased to 0.87-1.29 as a result of quarantine measures. Therefore, it can be expected that the spread of SARS-CoV-2 will be suppressed if 56%-64% of the total population becomes vaccinated or survives COVID-19.ConclusionsThe quarantine measures adopted in most countries are too weak compared to those previously used in China. Therefore, it is not expected that the spread of COVID-19 will stop and the disease will cease to exist naturally or owing to quarantine measures. Active vaccination of the population is needed to prevent the spread of COVID-19. Furthermore, the required specific percentage of vaccinated individuals depends on the magnitude of viral transmissibility, which can be evaluated using the proposed model and statistical data for the country of interest.     

Targeted preventive vaccination campaigns to reduce Ebola outbreaks: An individual-based modeling study

IntroductionNonpharmaceutical interventions (NPI) and ring vaccination (i.e., vaccination that primarily targets contacts and contacts of contacts of Ebola cases) are currently used to reduce the spread of Ebola during outbreaks. Because these measures are typically initiated after an outbreak is declared, they are limited by real-time implementation challenges. Preventive vaccination may provide a complementary option to help protect communities against unpredictable outbreaks. This study aimed to assess the impact of preventive vaccination strategies when implemented in conjunction with NPI and ring vaccination.MethodsA spatial-explicit, individual-based model (IBM) that accounts for heterogeneity of human contact, human movement, and timing of interventions was built to represent Ebola transmission in the Democratic Republic of the Congo. Simulated preventive vaccination strategies targeted healthcare workers (HCW), frontline workers (FW), and the general population (GP) with varying levels of coverage (lower coverage: 30% of HCW/FW, 5% of GP; higher coverage: 60% of HCW/FW, 10% of GP) and efficacy (lower efficacy: 60%; higher efficacy: 90%).ResultsThe IBM estimated that the addition of preventive vaccination for HCW reduced cases, hospitalizations, and deaths by ～11 % to ～25 % compared with NPI + ring vaccination alone. Including HCW and FW in the preventive vaccination campaign yielded ～14 % to ～38 % improvements in epidemic outcomes. Further including the GP yielded the greatest improvements, with ～21 % to ～52 % reductions in epidemic outcomes compared with NPI + ring vaccination alone. In a scenario without ring vaccination, preventive vaccination reduced cases, hospitalizations, and deaths by ～28 % to ～59 % compared with NPI alone. In all scenarios, preventive vaccination reduced Ebola transmission particularly during the initial phases of the epidemic, resulting in flatter epidemic curves.ConclusionsThe IBM showed that preventive vaccination may reduce Ebola cases, hospitalizations, and deaths, thus safeguarding the healthcare system and providing more time to implement additional interventions during an outbreak.     

Influenza vaccination uptake among Canadian adults before and during the COVID-19 pandemic: An analysis of the Canadian Longitudinal study on Aging (CLSA)

IntroductionUnderstanding how influenza vaccine uptake changed during the 2020/2021 influenza season compared to previous pre-pandemic seasons is a key priority, as is identifying the relationship between prior influenza vaccination and COVID-19 vaccine willingness.MethodsWe analyzed data from a large, nationally representative cohort of Canadian residents aged 50 and older to assess influenza vaccination status three times between 2015 and 2020. We investigated: 1) changes in self-reported influenza vaccine uptake, 2) predictors of influenza vaccine uptake in 2020/2021, and 3) the association between influenza vaccination history and self-reported COVID-19 vaccine willingness using logistic regression models.ResultsAmong 23,385 participants analyzed for aims 1–2, influenza vaccination increased over time: 14,114 (60.4%) in 2015–2018, 15,692 (67.1%) in 2019/2020, and 19,186 (82.0%; combining those already vaccinated and those planning to get a vaccine) in 2020/2021. After controlling for socio-demographics, history of influenza vaccination was most strongly associated with influenza vaccination in 2020/2021 (adjusted odds ratio [aOR] 147.9 [95% CI: 120.9–180.9]); this association remained after accounting for multiple health and pandemic-related factors (aOR 140.3 [95% CI: 114.5–171.8]). To a lesser degree, those more concerned about COVID-19 were also more likely to report influenza vaccination in fall 2020, whereas those reporting a very negative impact of the pandemic were less likely to get vaccinated. Among 23,819 participants with information on COVID-19 vaccine willingness during the last quarter of 2020 (aim 3), prior influenza vaccination was most strongly associated with willingness to get a COVID-19 vaccine (aOR 15.1 [95% CI: 13.5–16.8] for those who had received influenza vaccine at all previous timepoints versus none).ConclusionsOur analysis highlights the importance of previous vaccination in driving vaccination uptake and willingness. Efforts to increase vaccination coverage for influenza and COVID-19 should target individuals who do not routinely engage with immunization services regardless of demographic factors.     

上海市新型冠状病毒肺炎早期境外输入病例流行特征及防控措施分析

目的 分析上海市新型冠状病毒肺炎（COVID-19）早期境外输入病例流行特征及防控措施,为输入性疫情的防控工作提供参考依据。方法 资料来源于全国传染病报告信息管理系统截至2020年3月30日上海市COVID-19境外输入病例数据及上海市各级CDC流行病学调查报告,相关防控措施信息来源于政府相关部门官网及发布平台。采用EpiData 3.1、Excel 2019和SAS 9.4软件进行数据整理与统计学分析。结果 截至2020年3月30日,上海市累计报告境外输入病例171例（确诊病例170例,无症状感染者1例）。其中,中国籍122例（71.3%,122/171）,外籍49例（28.7%,49/171）;年龄中位数为23（P₂₅,P₇₅：18,35）岁,男女性别比为1.3∶1,学生占56.6%（97/171）;入境前发病者占45.6%（78/171）;临床分型为轻/普通型病例占96.5%（165/171）,中国籍和外籍病例的临床分型差异无统计学意义。流行曲线按确诊日期于3月24日达到峰值,随着防控措施“口岸联防联控机制闭环管理模式”落实,病例数逐渐下降。171例病例来源国主要为英国（37.3%,64例）、美国（18.6%,32例）、法国（11.0%,19例）和意大利（9.4%,16例）等24个国家及地区。需中转至国内21个省（自治区、直辖市）的病例占40.4%（69/171）。病例发现方式主要为海关检疫和社区留验点,分别占43.9%（75/171）和31.0%（53/171）。结论 上海市COVID-19早期境外输入病例以年轻人和学生为主,各国输入风险与其疫情严重程度基本一致。“口岸联防联控机制闭环管理模式”对境外输入病例的发现及管理效果明显。     

基于传染病动力学模型的宁波市新型冠状病毒肺炎防控措施效果评估

目的 基于传染病动力学模型评估宁波市新型冠状病毒肺炎（COVID-19）防控措施的效果。方法 收集截至2020年3月9日宁波市COVID-19疫情个案数据、疾病进程等信息。根据防控策略落实情况,建立SEIR传染病动力学模型,计算基本再生数（R₀）和实时再生数（R_t）,评估防控效果。结果 宁波市累计确诊COVID-19病例157例,无死亡病例,重症病例比例为12.1%。从暴露到发病（潜伏期）平均（5.7±2.9）d,发病到确诊平均（5.4±3.7）d,从确诊到出院平均（16.6±6.5）d。累计医学观察105 339人,其中居家医学观察者COVID-19感染率为0.1%,集中医学观察者感染率为0.3%,确诊病例在就诊前处于医学观察期者占63.1%。估算R₀为4.8。随着防控措施的加强,R_t呈逐渐下降趋势,到2月4日下降至1.0以下,之后持续下降到2月中旬的0.2。结论 通过建立传染病动力学模型,能够有效评估宁波市COVID-19防控措施的效果,为防控策略的制定提供科学依据。