Vaccine effectiveness against onward transmission of SARS-CoV2-infection by variant of concern and time since vaccination,Belgian contact tracing, 2021

BackgroundDuring the first half of 2021, we observed high vaccine effectiveness (VE) against SARS-CoV2-infection. The replacement of the alpha-‘variant of concern’ (VOC) by the delta-VOC and uncertainty about the time course of immunity called for a re-assessment.MethodsWe estimated VE against transmission of infection (VET) from Belgian contact tracing data for high-risk exposure contacts between 26/01/2021 and 14/12/2021 by susceptibility (VEs) and infectiousness of breakthrough cases (VEi) for a complete schedule of Ad26.COV2.S, ChAdOx1, BNT162b2, mRNA-1273 as well as infection-acquired and hybrid immunity. We used a multilevel Bayesian model and adjusted for personal characteristics (age, sex, household), background exposure, calendar week, VOC and time since immunity conferring-event.FindingsVET-estimates were higher for mRNA-vaccines, over 90%, compared to viral vector vaccines: 66% and 80% for Ad26COV2.S and ChAdOx1 respectively (Alpha, 0–50 days after vaccination). Delta was associated with a 40% increase in odds of transmission and a decrease of VEs (72–64%) and especially of VEi (71–46% for BNT162b2). Infection-acquired and hybrid immunity were less affected by Delta. Waning further reduced VET-estimates: from 81% to 63% for BNT162b2 (Delta, 150–200 days after vaccination). We observed lower initial VEi in the age group 65–84 years (32% vs 46% in the age group 45–64 years for BNT162b2) and faster waning. Hybrid immunity waned slower than vaccine-induced immunity.InterpretationVEi and VEs-estimates, while remaining significant, were reduced by Delta and waned over time. We observed faster waning in the oldest age group. We should seek to improve vaccine-induced protection in older persons and those vaccinated with viral-vector vaccines.     

Vaccine effectiveness against transmission of alpha,delta and omicron SARS-COV-2-infection,Belgian contact tracing, 2021–2022

ObjectivesVaccine effectiveness against transmission (VET) of SARS-CoV-2-infection can be estimated from secondary attack rates observed during contact tracing. We estimated VET, the vaccine-effect on infectiousness of the index case and susceptibility of the high-risk exposure contact (HREC).MethodsWe fitted RT-PCR-test results from HREC to immunity status (vaccine schedule, prior infection, time since last immunity-conferring event), age, sex, calendar week of sampling, household, background positivity rate and dominant VOC using a multilevel Bayesian regression-model. We included Belgian data collected between January 2021 and January 2022.ResultsFor primary BNT162b2-vaccination we estimated initial VET at 96% (95%CI 95–97) against Alpha, 87% (95%CI 84–88) against Delta and 31% (95%CI 25–37) against Omicron. Initial VET of booster-vaccination (mRNA primary and booster-vaccination) was 87% (95%CI 86–89) against Delta and 68% (95%CI 65–70) against Omicron. The VET-estimate against Delta and Omicron decreased to 71% (95%CI 64–78) and 55% (95%CI 46–62) respectively, 150–200 days after booster-vaccination. Hybrid immunity, defined as vaccination and documented prior infection, was associated with durable and higher or comparable (by number of antigen exposures) protection against transmission.ConclusionsWhile we observed VOC-specific immune-escape, especially by Omicron, and waning over time since immunization, vaccination remained associated with a reduced risk of SARS-CoV-2-transmission.     

传染性与分娩方式对HBV母婴垂直传播的影响

目的探讨孕妇不同传染性与分娩方式对HBV母婴垂直传播的影响。方法将409例HBsAg阳性孕妇分为HBeAg阳性组与HBeAg阴性组，同时按照分娩方式分为剖宫产组与阴道分娩组，新生儿出生1小时内检测股静脉血，HBsAg阳性和（或）HBVDNA阳性为宫内感染。结果HBeAg阳性与HBeAg阴性两组感染率分别为17．5％和7．2％，两组比较有极其显著的差异（P〈0．01）。其中HBeAg阴性组阴道分娩与剖宫产分娩的感染率分别为14．7％和2．7％，差异具有统计学意义（P〈0．05）。结论HBeAg阳性母亲其新生儿HBV感染率显著高于HBeAg阴性母亲，HBeAg阴性组剖宫产分娩新生儿感染率低于阴道分娩。     

传染性标志物检测结果阶段性回顾

目的：明确血源性传染性标志物检测在医疗损伤性感染防护和规避医疗纠纷的重要意义,探讨其流行趋势及意义。方法：对在潜江市中心医院采用酶联免疫吸附（ELISA）法检测的血液传染性标记物（乙肝表面抗原（HBsAg）、丙肝抗体（抗-HCV）、艾滋病病毒1/2抗体（抗-HIV1/2）,梅毒螺旋体特异性抗体）相关资料进行阶段性回顾。结果：在88 669份血清标本中,HBsAg阳性血清为12 857例,阳性率为14.5%,明显高于正常人群平均水平;丙肝抗体阳性率为0.42%;艾滋病病毒抗体1/2初筛阳性率为0.06%,梅毒螺旋体抗体（TP-Ab）阳性率为1.08%。结论：潜江地区病原体感染以HBV为主,但有逐年下降的趋势;HCV、HIV和TP感染形势严峻。     

新型冠状病毒肺炎无症状感染者在疫情传播中的作用与防控策略

新型冠状病毒肺炎（新冠肺炎）无症状感染者成为我国防控疫情反弹的热点问题。本文介绍新冠肺炎无症状感染者现象、定义、发现过程与疫情报告和统计规则，阐述初诊为无症状感染者在跟踪观察一个最长潜伏期后，病情自然发展变化将其化分为隐性感染无症状感染者和潜伏期无症状感染者两大类，利用现有数据分析无症状感染者的传染性及其对疫情传播扩散的作用，探讨我国防止无症状感染者可能造成疫情反弹所面临的挑战，并提出防控及研究相关建议。     

High levels of Trypanosoma cruzi DNA determined by qPCR and infectiousness to Triatoma infestans support dogs and cats are major sources of parasites for domestic transmission

The competence of reservoir hosts of vector-borne pathogens is directly linked to its capacity to infect the vector. Domestic dogs and cats are major domestic reservoir hosts of Trypanosoma cruzi, and exhibit a much higher infectiousness to triatomines than seropositive humans. We quantified the concentration of T. cruzi DNA in the peripheral blood of naturally-infected dogs and cats (a surrogate of intensity of parasitemia), and evaluated its association with infectiousness to the vector in a high-risk area of the Argentinean Chaco. To measure infectiousness, 44 infected dogs and 15 infected cats were each exposed to xenodiagnosis with 10–20 uninfected, laboratory-reared Triatoma infestans that blood-fed to repletion and were later individually examined for infection by optical microscopy. Parasite DNA concentration (expressed as equivalent amounts of parasite DNA per mL, Pe/mL) was estimated by real-time PCR amplification of the nuclear satellite DNA. Infectiousness increased steeply with parasite DNA concentration both in dogs and cats. Neither the median parasite load nor the mean infectiousness differed significantly between dogs (8.1 Pe/mL and 48%) and cats (9.7 Pe/mL and 44%), respectively. The infectiousness of dogs was positively and significantly associated with parasite load and an index of the host’s body condition, but not with dog’s age, parasite discrete typing unit and exposure to infected bugs in a random-effects multiple logistic regression model. Real-time PCR was more sensitive and less time-consuming than xenodiagnosis, and in conjunction with the body condition index, may be used to identify highly infectious hosts and implement novel control strategies.     

急腹症并感染性休克的临床诊治分析

目的：探讨急腹症并感染性休克的临床诊治方法。方法：根据我院的处理急腹症并感染性休克的经验，在对32例的急腹症并感染性休克的例子中手术治疗28例，治愈人数为19手术的治愈率在67%，非手术治疗4例，治愈1例。在进行此次的分析中治愈20例，治愈率为62．05％，治愈失败的原因主要在于患者的脏器受损，多处脏器的功能发生障碍。结论：在治疗急腹症并感染-挂休克的临床急诊中，要慎重使用抗生素等药物，注意防治身体脏器的同时受损。     

组织切片病理申请单HBsAg和HBV-DNA检测初步探讨

目的 :了解传染病医院病理科的组织切片 ,病理申请单是否受到 HBV污染和是否具有传染性。方法 :随机采集传染病医院组织切片、病理申请单各 5 0张 ,用标准固体表面 HBV采样法取样 ,EL ISA法检测 HBs Ag,斑点杂交法检测HBV- DNA。结果 :组织切片 HBs Ag ( ) 15例 (30 % ) ,病理申请单 HBs Ag ( ) 14例 (2 8% ) ;组织切片、病理申请单HBV- DNA检测均为阴性。结论 :传染病医院的组织切片、病理申请单有相当数量被 HBV污染 ,但传染性较小。     

Quantitative differences in the infectiousness and pathocenicity of 187 Salmonella serotypies or species

The present paper makes use of the epidemiological statistical data from 372,496 salmonellae isolated in man and 63,345 isolations from non-human material, e.g. animal foodstuffs, domestic animals and food of animal origin, surface waters and drainage waters. There were a total of 187 different serotypes. The data are derived from publications of the Federal Health Office, Berlin, for the period 1972–76; the Center for Disease Control, Atlanta, Georgia for the years 1968–74; and from various publications and our own studies between 1954–76.On the basis of theoretical deduction and by inductive procedures, Salmonella quotients were derived as quantitative statistical values for the infectiousness or pathogenicity of the individual serotypes in man or in animals. They result from the relative frequency of a serotype in man in relation to the relative frequency in non-human material, in animal food or surface water. The Salmonella quotients for the pathogenicity in animals can also be calculated in a similar way.The values vary about the factor 10⁵ in the individual serotypes It is inferred from this that infectiousness and pathogenicity vary by the same order of size. The Salmonella quotients are constant over many years and evidently also all over the world for most serotypes. Salmonella quotients with numerical values less than 1 indicate a depletion of the corresponding serotype in man. Numerical values greater than 1 indicate an accumulation. Conclusions can hence be drawn with regard to lower or higher infectiousness and pathogenicity.     

Microcavia australis (Caviidae,Rodentia), a new highly competent host of Trypanosoma cruzi I in rural communities of northwestern Argentina

Rodents are well-known hosts of Trypanosoma cruzi but little is known on the role of some caviomorph rodents. We assessed the occurrence and prevalence of T. cruzi infection in Microcavia australis (“southern mountain, desert or small cavy”) and its infectiousness to the vector Triatoma infestans in four rural communities of Tafí del Valle department, northwestern Argentina. Parasite detection was performed by xenodiagnosis and polymerase chain reaction amplification of the hyper-variable region of kinetoplast DNA minicircles of T. cruzi (kDNA-PCR) from blood samples. A total of 51 cavies was captured in traps set up along cavy paths in peridomestic dry-shrub fences located between 25 and 85 m from the nearest domicile. We document the first record of M. australis naturally infected by T. cruzi. Cavies presented a very high prevalence of infection (46.3%; 95% confidence interval, CI = 33.0–59.6%). Only one (4%) of 23 cavies negative by xenodiagnosis was found infected by kDNA-PCR. TcI was the only discrete typing unit identified in 12 cavies with a positive xenodiagnosis. The infectiousness to T. infestans of cavies positive by xenodiagnosis or kDNA-PCR was very high (mean, 55.8%; CI = 48.4–63.1%) and exceeded 80% in 44% of the hosts. Cavies are highly-competent hosts of T. cruzi in peridomestic habitats near human dwellings in rural communities of Tucumán province in northwestern Argentina.