宁波市新型冠状病毒再感染的流行病学特征及其影响因素

目的 分析新型冠状病毒（新冠病毒）再感染的流行病学特征及其影响因素，为科学防控新冠病毒感染疫情提供依据。方法 在中国疾病预防控制信息系统的传染病监测系统获取2020年1月1日至2022年11月30日宁波市新冠病毒既往感染者的资料，对其再感染状况进行问卷调查，采用多因素logistic回归分析性别、年龄、距初次感染时间间隔、新冠病毒疫苗接种剂次及基础疾病史对新冠病毒再感染的影响。结果 共调查897例既往感染者，其中115例再感染者，再感染率为12.82%。再感染者两次感染间隔时间M（Q₁，Q₃）为1 052（504，1 056）d。单因素分析显示，年龄、新冠病毒疫苗接种剂次、初次感染变异株类型、距初次感染时间间隔、初次感染严重程度与再感染率有关（均P<0.05）。多因素logistic回归分析显示，30~岁组再感染发生风险高于≥60岁组（OR=2.10，95%CI：1.11~3.97）； 距初次感染<6个月组无再感染发生，≥12个月组再感染发生风险高于6~个月组（OR=6.68，95%CI：3.46~12.90）；初次感染严重程度为普通型和轻型者再感染发生风险高于无症状感染者（OR=2.64，95%CI：1.18~5.88；OR=2.79，95%CI：1.27~6.11）。结论 距初次感染时间间隔是再感染风险的重要影响因素，6个月内出现再感染的概率较低。     

新型冠状病毒灭活疫苗不同接种间隔的免疫原性和安全性研究

目的 比较公安人员按不同方案（0~14 d、0~21 d、0~28 d）接种新型冠状病毒（新冠病毒）灭活疫苗的免疫原性和安全性。方法 于2021年1-2月以山西省太原市405名公安人员为研究对象,通过随机分组将其分为3组,分别按照0~14 d、0~21 d和0~28 d方案接种2剂新冠病毒灭活疫苗,采用RT-PCR检测新冠病毒核酸,活病毒微量病变法检测新冠病毒中和抗体,分析3组的新冠病毒中和抗体GMT、血清阳转率和安全性。结果 0~14 d、0~21 d和0~28 d方案组新冠病毒中和抗体血清学阳转率均为100%,其中0~21 d组[166.70（95%CI：148.30~185.10）]和0~28 d组[179.50（95%CI：156.50~202.60）]新冠病毒中和抗体水平接近（P>0.05）,均明显高于0~14 d组[86.08（95%CI：72.36~99.80）]（P<0.001）。3个方案组不良反应发生率分别为1.48%（2/135）、0.74%（1/136）和1.49%（2/134）（P=0.750）,均为轻度不良反应。结论 公安人员按不同方案（0~14 d、0~21 d、0~28 d）接种新冠病毒灭活疫苗后均表现出较好的血清阳转率和安全性,0~21 d和0~28 d接种方案组新冠病毒中和抗体GMT高于0~14 d方案组。     

3~11岁儿童接种新型冠状病毒灭活疫苗的免疫原性研究

目的 评价3~11岁儿童完成新型冠状病毒（新冠病毒）疫苗基础免疫28~42 d后对原始株的免疫原性及与新冠病毒变异株的交叉免疫反应。方法 于2022年1-7月在山东省乳山市招募3~11岁已按照（0,28）d免疫程序完成2剂新冠病毒灭活疫苗基础免疫的受试者,基础免疫后28~42 d采集静脉血3 ml,检测原始株、Beta、Gamma和Delta变异株的中和抗体水平,计算中和抗体阳性率和GMT。结果 纳入免疫原性分析共395人,其中3~5岁组212人,6~11岁组183人。受试者完成基础免疫后28~42 d,血清中对原始株、Beta、Gamma和Delta变异株的中和抗体阳性率分别为100.00%、74.68%、99.24%和97.22%,年龄组间差异无统计学意义（P>0.05）。受试者完成基础疫苗后28~42 d,血清中对原始株、Beta、Gamma和Delta变异株的中和抗体GMT分别为168.19、10.51、53.65和31.10,年龄组间差异无统计学意义（P>0.05）。结论 在3~11岁儿童中接种2剂新冠病毒灭活疫苗的免疫原性良好,可对新冠病毒变异株产生一定的交叉保护。     

苏州市新型冠状病毒既往感染者再感染情况调查分析

目的 了解新型冠状病毒（新冠病毒）既往感染者的再感染率，比较分析再感染者和初次感染者的疾病严重程度及预后。方法 对2020年1月22日至2022年11月8日苏州市报告的新冠病毒既往感染者开展2022年12月8日至2023年1月18日新冠病毒感染情况问卷调查。1∶2成组匹配，从苏州市新冠病毒感染社区随访队列人群中选取与再感染者居住社区、年龄组和性别相同的初次感染者，采用χ²检验比较再感染者和初次感染者感染后的临床症状和预后情况。结果 既往感染者的再感染率为13.01%（147/1 130）；初次感染1~6个月未发现再感染者，距初次感染间隔时间7~12个月和≥24个月者再感染率分别为10.59%（95/897）和45.61%（52/114）。完成新冠病毒疫苗加强免疫4剂次的既往感染者再感染率最低（9.09%，1/11）。再感染者感染后出现的主要症状与初次感染者基本相同，除干咳、恶心/纳差和其他症状外，其余各项临床症状在两组间差异有统计学意义（均P<0.05），最高体温低于初次感染者且发热持续时间短。再感染者的就诊率为4.08%（6/147），低于初次感染者的11.56%（34/294）。再感染者感染后核酸/抗原转阴时间和自我感觉明显好转/症状基本消失时间短于初次感染者。结论 新冠病毒既往感染者中存在再感染，再感染距初次感染的间隔时间和疫苗加强免疫4剂次是再感染率的影响因素；再感染者较初次感染者就诊率低，症状较轻、感染后恢复更快。     

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。     

3岁及以上人群新型冠状病毒灭活疫苗接种反应临床观察分析

目的 评价贵州省≥3岁人群接种新型冠状病毒（新冠病毒）灭活疫苗的安全性。方法 采用开放式设计，于2021年6月至2022年7月在贵州省沿河县招募符合条件的人群，按照（0，28）d免疫程序接种2剂次新冠病毒灭活疫苗，收集每剂次疫苗接种后30 min内和0~28 d的不良反应，分年龄、剂次、患病情况分析不良反应发生率。结果 总不良反应发生率为1.51%（294/19 458），所有不良反应均发生在接种后7 d内，严重程度为1级或2级，以接种部位疼痛最常见。3~、18~和≥60岁组不良反应发生率分别为1.01%（58/5 721）、2.44%（220/9 017）和0.34%（16/4 720），差异有统计学意义（P<0.001）。第1剂次接种后不良反应发生率（1.20%，233/19 458）高于第2剂次（0.37%，61/16 368），差异有统计学意义（P<0.001）。≥60岁组中健康人群和患基础疾病人群不良反应发生率分别为0.36%（9/2 520）和0.32%（7/2 200），差异无统计学意义（P=0.818）。结论 ≥3岁人群接种新冠病毒灭活疫苗安全性良好，在老年健康人群和患基础疾病人群中接种均具有良好安全性。     

某外籍货轮进口冷冻海鲜新型冠状病毒污染状况及其装卸工人感染危险因素调查

目的 调查青岛市俄罗斯籍货轮进口冷冻海鲜的污染状况，分析其装卸工人感染的危险因素。方法 对进口冷冻海鲜采用"两阶段、全覆盖、混采"的方法采集样本分析其污染情况，采用实时荧光定量RT-PCR法进行新型冠状病毒（新冠病毒）核酸检测；设计统一的调查问卷，对71名装卸工人开展电话调查。调查对象分为2组：报告2例新冠病毒无症状感染者的工作班组（A组工人，23名）；未报告新冠病毒感染者的工作班组（B组工人，48名）。采用Epi Info7.2软件分析装卸工人新冠病毒感染的相关危险因素。结果 俄罗斯籍货轮的装卸货物全部为进口冷冻海鲜，货物的新冠病毒核酸阳性率为11.53%（106/919）。A组工人装卸的进口冷冻海鲜中，新冠病毒核酸阳性率为14.29%（70/490），明显高于B组工人的8.39%（36/429）（χ²=7.79，P=0.01），且A组工人装卸的进口冷冻海鲜的新冠病毒载量明显高于B组（P<0.05），A组工人的个人防护和行为得分明显低于B组（P<0.05）；装卸工人搬运过程有上厕所、吸烟、饭前未规范洗手的行为是新冠病毒感染的危险因素。结论 该批俄罗斯进口冷冻海鲜存在新冠病毒污染，且污染分布不均匀，应加强进口冷链从业人员的职业个人防护及行为的监督和管理。建议海洋渔业部门建立从业人员及运输货物的"捕捞-运输-装卸"全程闭环监测管理体系。     

构建大规模人群新型冠状病毒核酸筛查指标体系研究

目的 建立适用于大规模人群新型冠状病毒（新冠病毒）核酸筛查时,科学确定筛查范围的指标体系。方法 采用文献检索和头脑风暴法,拟定大规模人群新冠病毒核酸筛查指标体系初始框架和指标,通过层次分析法及Delphi法结合的方式,对全国21名专家进行两轮咨询,确定大规模人群新冠病毒核酸筛查指标体系及权重。结果 两轮咨询的专家积极指数均为100%,权威系数（Cr）分别为0.88±0.08、0.89±0.07,变异系数（CV）范围（0.08,0.24）、（0.09,0.25）;Kendall''s W协调系数分别为0.34、0.22,差异有统计学意义（χ²=97.02、249.90,P<0.05）。最终确立了包括4个一级指标、11个二级指标、58个三级指标的大规模人群新冠病毒核酸筛查指标体系,并确定了各指标权重。结论 初步建立了大规模人群新冠病毒核酸筛查指标体系,对卫生行政部门科学和精准地确定大规模人群筛查范围时提供参考依据。     

上海市新型冠状病毒肺炎流行与疫情时空变化分析

目的 阐明2022年上海市新型冠状病毒肺炎（新冠肺炎）的流行特征和空间聚集性演变规律。方法 收集2022年3月1日至5月31日上海市各行政区卫生健康委员会官方网站公布的新冠肺炎疫情数据，应用GeoDa软件进行空间自相关分析；利用logistic增长模型进行拟合预测并与实际感染病例进行对比。结果 上海市各行政区中，浦东新区确诊病例数和无症状感染者人数最多，占总病例数的29.30%和35.58%，各区累计罹患率和感染率差异有统计学意义（P<0.001），其中黄浦区显著高于其他区域。2022年3月1日至5月31日新冠肺炎罹患率具有全局空间正相关性（P<0.05），不同时段新冠肺炎罹患率空间分布不同，其中3月16-29日、4月6-12日和5月18-24日3个时段内Moran''s I值差异无统计学意义（P>0.05）。局部自相关分析结果表明，8个时段共探测到22个高-高聚集区，高风险流行的热点区域经历一个“少-多-少”的变化过程。logistic增长模型拟合与实际感染者情况基本吻合。结论 本轮上海市新冠肺炎疫情整体分布具有明显的空间聚集性，防控措施有效阻止了疫情的增长，尤其在空间上遏制了高风险传播区域的扩散，减少了向其他省份的传播风险。     

北京市新型冠状病毒Omicron BA.2和BF.7变异株感染者潜伏期特征分析

目的 对北京市由新型冠状病毒（新冠病毒）Omicron BA.2和BF.7变异株引起的疫情中的感染者进行流行病学调查，估算2种变异株分支的潜伏期及其影响因素，为新冠病毒传播动力学模型的建立提供基本参数。方法 选取北京市2022年4月（Omicron BA.2变异株）及10月（Omicron BF.7变异株）疫情中具有明确暴露时间和发病时间的感染者进行研究，采用秩和检验对不同变异株的潜伏期差异进行分析。使用Weibull、Gamma和lognormal分布对Omicron变异株的潜伏期分布进行拟合。采用多因素方差分析比较不同年龄、性别、变异株类型及疫苗接种状态下的潜伏期。结果 共纳入64例BA.2变异株感染者及58例BF.7变异株感染者。BA.2和BF.7变异株感染者潜伏期M（Q₁，Q₃）分别为3.00（3.00，4.00）d和3.00（2.00，3.25）d。lognormal分布的拟合效果最佳。多因素方差分析结果显示，不同类型的Omicron变异株潜伏期存在一定差异，与BA.2变异株感染者相比，BF.7变异株感染者的潜伏期更短。结论 Omicron BF.7变异株感染者潜伏期较BA.2变异株的潜伏期短。     

北京市境外输入性新型冠状病毒感染者的流行特征分析

目的分析北京市境外输入性新型冠状病毒(新冠病毒)感染者的流行病学特征及疫苗接种对感染者病毒载量和疾病严重程度的影响。方法数据来源于中国疾病预防控制信息系统传染病报告信息管理系统和现场流行病学调查, 应用Excel 2010和SPSS 22.0软件进行数据整理和统计学分析。结果 2021年6月1日至9月30日, 北京市累计报告171例境外输入性新冠病毒感染者, 无症状感染者占66.67%(114/171)。输入国以菲律宾、阿联酋、英国和俄罗斯为主, 占67.84%(116/171)。感染者男女性别比为2∶1(114∶57);年龄M(Q1, Q3)为28(23, 36)岁;中国籍占80.12%(137/171)。对其中47例进行病毒全基因组测序, 76.60%(36/47)属于Delta变异株。疫苗接种率为60.82%(104/171), 其中疫苗全程接种率为53.80%(92/171)。13.53%(23/170)的感染者入境当天筛查出核酸阳性, 所有感染者均在28 d内检测出核酸阳性。未接种组疾病严重程度高于未全程接种组和全程接种组(P<0.001), 出现了1例重型和1例危重型...     

SARS-CoV-2 infection risk among vaccinated and unvaccinated household members during the Alpha variant surge – Denver,Colorado, and San Diego,California, January–April 2021

BackgroundCOVID-19 vaccination reduces SARS-CoV-2 infection and transmission. However, evidence is emerging on the degree of protection across variants and in high-transmission settings. To better understand the protection afforded by vaccination specifically in a high-transmission setting, we examined household transmission of SARS-CoV-2 during a period of high community incidence with predominant SARS-CoV-2 B.1.1.7 (Alpha) variant, among vaccinated and unvaccinated contacts.MethodsWe conducted a household transmission investigation in San Diego County, California, and Denver, Colorado, during January-April 2021. Households were enrolled if they had at least one person with documented SARS-CoV-2 infection. We collected nasopharyngeal swabs, blood, demographic information, and vaccination history from all consenting household members. We compared infection risks (IRs), RT-PCR cycle threshold values, SARS-CoV-2 culture results, and antibody statuses among vaccinated and unvaccinated household contacts.ResultsWe enrolled 493 individuals from 138 households. The SARS-CoV-2 variant was identified from 121/138 households (88%). The most common variants were Alpha (75/121, 62%) and Epsilon (19/121, 16%). There were no households with discordant lineages among household members. One fully vaccinated secondary case was symptomatic (13%); the other 5 were asymptomatic (87%). Among unvaccinated secondary cases, 105/108 (97%) were symptomatic. Among 127 households with a single primary case, the IR for household contacts was 45% (146/322; 95% Confidence Interval [CI] 40–51%). The observed IR was higher in unvaccinated (130/257, 49%, 95% CI 45–57%) than fully vaccinated contacts (6/26, 23%, 95% CI 11–42%). A lower proportion of households with a fully vaccinated primary case had secondary cases (1/5, 20%) than households with an unvaccinated primary case (66/108, 62%).ConclusionsAlthough SARS-CoV-2 infections in vaccinated household contacts were reported in this high transmission setting, full vaccination protected against SARS-CoV-2 infection. These findings further support the protective effect of COVID-19 vaccination and highlight the need for ongoing vaccination among eligible persons.     

COVID-19 outbreak in an elderly care home: Very low vaccine effectiveness and late impact of booster vaccination campaign

BackgroundElderly people in long-term care facilities (LTCF) are at higher risk for (severe) COVID-19, yet evidence of vaccine effectiveness (VE) in this population is scarce. In November 2021 (Delta period), a COVID-19 outbreak occurred at a LTCF in the Netherlands, continuing despite measures and booster vaccination campaign. We investigated the outbreak to assess VE of primary COVID-19 vaccination against SARS-CoV-2 infection and mortality, and to describe the impact of the booster vaccination.MethodsWe calculated attack rate (AR) and case fatality (CF) per vaccination status (unvaccinated, primarily vaccinated and boostered). We calculated VE – at on average 6 months after vaccination – as 1- risk ratio (RR) using the crude risk ratio (RR) with 95% confidence intervals (CI) for the association between vaccination status (primary vaccination versus unvaccinated) and outcomes (SARS-CoV-2 infection and mortality < 30 days after testing positive for SARS-CoV-2).ResultsThe overall AR was 67% (70/105). CF was 33% (2/6) among unvaccinated cases, 12% among primarily vaccinated (7/58) and 0% (0/5) among boostered. The VE of primary vaccination was 17% (95% CI ?28%; 46%) against SARS-CoV-2 infection and 70% (95% CI ?44%; 96%) against mortality. Among boostered residents (N = 55), there were 25 cases in the first week after receiving the booster dose, declining to 5 in the second and none in the third week.ConclusionVE of primary vaccination in residents of LTCF was very low against SARS-CoV-2 infection and moderate against mortality. There were few cases at 2 weeks after the booster dose and no deaths, despite the presence of susceptible residents. These data are consistent with the positive impact of the booster vaccination in curbing transmission. Timely booster vaccination in residents of LTCF is therefore important.     

接种灭活疫苗后的境外输入性新冠肺炎患者临床特征

目的 通过比较接种/未接种新型冠状病毒灭活疫苗(Vero细胞)后感染新型冠状病毒(COVID-19)的境外输入性患者的临床特征,为临床诊疗提供参考.方法 选取2021年1月4日—4月10日广州医科大学附属市八医院收治的接种灭活疫苗后境外输入性COVID-19患者(接种疫苗组),及同期来自相同输入国家的未接种新冠疫苗的确...     

Short-term safety of COVID-19 mRNA vaccines with respect to all-cause mortality in the older population in Norway

BackgroundThere have been concerns about COVID-19 vaccination safety among frail older individuals. We investigated the relationship between COVID-19 mRNA vaccination and mortality among individuals aged ≥ 70 years and whether mortality varies across four groups of health services used.MethodsIn this nationwide cohort study, we included 688,152 individuals aged ≥ 70 years at the start of the Norwegian vaccination campaign (December 27, 2020). We collected individual-level data from the Norwegian Emergency Preparedness Register for COVID-19. Vaccinated and unvaccinated individuals were matched (1:1 ratio) on the date of vaccination based on sociodemographic and clinical characteristics. The main outcome was all-cause mortality during 21 days after first dose of COVID-19 mRNA vaccination. Kaplan-Meier survival functions were estimated for the vaccinated and unvaccinated groups. We used Cox proportional-hazards regression to estimate hazard ratios (HRs) of death between vaccinated and unvaccinated individuals, with associated 95% confidence intervals (CIs), overall and by use of health services (none, home-based, short- and long-term nursing homes) and age group.ResultsBetween December 27, 2020, and March 31, 2021, 420,771 older individuals (61.1%) were vaccinated against COVID-19. The Kaplan-Meier estimates based on the matched study sample showed a small absolute risk difference in all-cause mortality between vaccinated and unvaccinated individuals, with a lower mortality in the vaccinated group (overall HR 0.28 [95% CI: 0.24–0.31]). Similar results were obtained in analyses stratified by use of health services and age group.ConclusionWe found no evidence of increased short-term mortality among vaccinated individuals in the older population after matching on sociodemographic and clinical characteristics affecting vaccination and mortality.     

Assessing COVID-19 Vaccine Uptake and Effectiveness Through the North West London Vaccination Program: Retrospective Cohort Study

BackgroundOn March 11, 2020, the World Health Organization declared SARS-CoV-2, causing COVID-19, as a pandemic. The UK mass vaccination program commenced on December 8, 2020, vaccinating groups of the population deemed to be most vulnerable to severe COVID-19 infection.ObjectiveThis study aims to assess the early vaccine administration coverage and outcome data across an integrated care system in North West London, leveraging a unique population-level care data set. Vaccine effectiveness of a single dose of the Oxford/AstraZeneca and Pfizer/BioNTech vaccines were compared.MethodsA retrospective cohort study identified 2,183,939 individuals eligible for COVID-19 vaccination between December 8, 2020, and February 24, 2021, within a primary, secondary, and community care integrated care data set. These data were used to assess vaccination hesitancy across ethnicity, gender, and socioeconomic deprivation measures (Pearson product-moment correlations); investigate COVID-19 transmission related to vaccination hubs; and assess the early effectiveness of COVID-19 vaccination (after a single dose) using time-to-event analyses with multivariable Cox regression analysis to investigate if vaccination independently predicted positive SARS-CoV-2 in those vaccinated compared to those unvaccinated.ResultsIn this study, 5.88% (24,332/413,919) of individuals declined and did not receive a vaccination. Black or Black British individuals had the highest rate of declining a vaccine at 16.14% (4337/26,870). There was a strong negative association between socioeconomic deprivation and rate of declining vaccination (r=–0.94; P=.002) with 13.5% (1980/14,571) of individuals declining vaccination in the most deprived areas compared to 0.98% (869/9609) in the least. In the first 6 days after vaccination, 344 of 389,587 (0.09%) individuals tested positive for SARS-CoV-2. The rate increased to 0.13% (525/389,243) between days 7 and 13, before then gradually falling week on week. At 28 days post vaccination, there was a 74% (hazard ratio 0.26, 95% CI 0.19-0.35) and 78% (hazard ratio 0.22, 95% CI 0.18-0.27) reduction in risk of testing positive for SARS-CoV-2 for individuals that received the Oxford/AstraZeneca and Pfizer/BioNTech vaccines, respectively, when compared with unvaccinated individuals. A very low proportion of hospital admissions were seen in vaccinated individuals who tested positive for SARS-CoV-2 (288/389,587, 0.07% of all patients vaccinated) providing evidence for vaccination effectiveness after a single dose.ConclusionsThere was no definitive evidence to suggest COVID-19 was transmitted as a result of vaccination hubs during the vaccine administration rollout in North West London, and the risk of contracting COVID-19 or becoming hospitalized after vaccination has been demonstrated to be low in the vaccinated population. This study provides further evidence that a single dose of either the Pfizer/BioNTech vaccine or the Oxford/AstraZeneca vaccine is effective at reducing the risk of testing positive for COVID-19 up to 60 days across all age groups, ethnic groups, and risk categories in an urban UK population.     

COVID-19 vaccine confidence and reasons for vaccination among health care workers and household members

BackgroundThe majority of healthcare workers (HCW) in the US report being fully vaccinated against COVID-19, yet little is known about vaccine decision-making for their household members, including children.MethodsCross-sectional survey July–August 2021 of HCW and their household members in Minnesota.Results94 % of eligible participants were vaccinated with the most common reasons being wanting to protect oneself, family and loved ones. Safety concerns were the most commonly reported reasons for not being vaccinated; a significantly higher proportion of unvaccinated compared to vaccinated HCW (58 % vs 12 %, p = 0.0035) and household adults (25 % vs 5 %, p = 0.03) reported prior SARS-CoV-2 infection. Nearly half of unvaccinated adults and two-thirds of unvaccinated children would be vaccinated if a vaccine mandate were in place.ConclusionsDespite high COVID-19 vaccine acceptance among HCWs, more research is required to identify and address the needs and concerns of healthcare workers who decline COVID-19 vaccination despite availability.     

Vaccine effectiveness against COVID-19 related hospital admission in the Netherlands: A test-negative case-control study

IntroductionReal-world vaccine effectiveness (VE) estimates are essential to identify potential groups at higher risk of break-through infections and to guide policy. We assessed the VE of COVID-19 vaccination against COVID-19 hospitalization, while adjusting and stratifying for patient characteristics.MethodsWe performed a test-negative case-control study in six Dutch hospitals. The study population consisted of adults eligible for COVID-19 vaccination hospitalized between May 1 and June 28, 2021 with respiratory symptoms. Cases were defined as patients who tested positive for SARS-CoV-2 by PCR during the first 48 h of admission or within 14 days prior to hospital admission. Controls were patients tested negative at admission and did not have a positive test during the 2 weeks prior to hospitalization. VE was calculated using multivariable logistic regression, adjusting for calendar week, sex, age, comorbidity and nursing home residency. Subgroup analysis was performed for age, sex and different comorbidities. Secondary endpoints were ICU-admission and mortality.Results379 cases and 255 controls were included of whom 157 (18%) were vaccinated prior to admission. Five cases (1%) and 40 controls (16%) were fully vaccinated (VE: 93%; 95% CI: 81 – 98), and 40 cases (11%) and 70 controls (27%) were partially vaccinated (VE: 70%; 95% CI: 50–82). A strongly protective effect of vaccination was found in all comorbidity subgroups. No ICU-admission or mortality were reported among fully vaccinated cases. Of unvaccinated cases, mortality was 10% and 19% was admitted at the ICU.ConclusionCOVID-19 vaccination provides a strong protective effect against COVID-19 related hospital admission, in patients with and without comorbidity.     

Factors associated with COVID-19 vaccination during June–October 2021: A multi-site prospective study

IntroductionVaccine hesitancy presents a challenge to COVID-19 control efforts. To identify beliefs associated with delayed vaccine uptake, we developed and implemented a vaccine hesitancy survey for the COVID-19 Community Research Partnership.MethodsIn June 2021, we assessed attitudes and beliefs associated with COVID-19 vaccination using an online survey. Self-reported vaccination data were requested daily through October 2021. We compared responses between vaccinated and unvaccinated respondents using absolute standardized mean differences (ASMD). We assessed validity and reliability using exploratory factor analysis and identified latent factors associated with a subset of survey items. Cox proportional hazards models and mediation analyses assessed predictors of subsequent vaccination among those initially unvaccinated.ResultsIn June 2021, 29,522 vaccinated and 1,272 unvaccinated participants completed surveys. Among those unvaccinated in June 2021, 559 (43.9 %) became vaccinated by October 31, 2021. In June, unvaccinated participants were less likely to feel “very concerned” about getting COVID-19 than vaccinated participants (10.6 % vs. 43.3 %, ASMD 0.792). Among those initially unvaccinated, greater intent to become vaccinated was associated with getting vaccinated and shorter time to vaccination. However, even among participants who reported no intention to become vaccinated, 28.5 % reported vaccination before study end. Two latent factors predicted subsequent vaccination—being ‘more receptive’ was derived from motivation to protect one’s own or others’ health and resume usual activities; being ‘less receptive’ was derived from concerns about COVID-19 vaccines. In a Cox model, both factors were partially mediated by vaccination intention.ConclusionThis study characterizes vaccine hesitant individuals and identifies predictors of eventual COVID-19 vaccination through October 31, 2021. Even individuals with no intention to be vaccinated can shift to vaccine uptake. Our data suggest factors of perceived severity of COVID-19 disease, vaccine safety, and trust in the vaccine development process are predictive of vaccination and may be important opportunities for ongoing interventions.