SARS-CoV-2 Transmission Dynamics in Households With Children, Los Angeles, California

Objectives: Studies of household transmission of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) focused on households with children are limited. We investigated household secondary attack rate (SAR), transmission dynamics, and contributing factors in households with children.Materials and Methods: In this prospective case-ascertained study in Los Angeles County, California, all households members were enrolled if ≥1 member tested positive for SARS-CoV-2 by polymerase chain reaction (PCR). Nasopharyngeal PCRs, serology, and symptom data were obtained over multiple visits.Results: A total of 489 individuals in 105 households were enrolled from June to December 2020. The majority (77.3%) reported a household annual income of <$50,000, and most (92.9%) were of Hispanic/Latinx ethnicity. Children <18 years old accounted for 46.9% index cases, of whom 45.3% were asymptomatic. Household index cases were predominantly children during low community transmission and adults during the high community transmission period (χ2 = 7.647, p = 0.0036. The mean household SAR was 77.0% (95% CI: 69.4–84.6%). Child and adult index cases both efficiently transmitted SARS-CoV-2 within households [81.9%, (95% CI: 72.1–91.9%) vs. 72.4% (95% CI: 59.8–85.1%), p = 0.23]. Household income and pets were significantly associated with higher SAR in the multivariable analysis of household factors (p = 0.0013 and 0.004, respectively).Conclusions: The SAR in households with children in an urban setting with a large ethnic minority population is much higher than previously described. Children play important roles as index cases. SAR was disproportionately impacted by household income. Vaccination and public health efforts need special focus on children and vulnerable communities to help mitigate SARS-CoV-2 spread.

Singleton exome sequencing of 90 fetuses with ultrasound anomalies revealing novel disease-causing variants and genotype–phenotype correlations

Exome sequencing has been increasingly implemented in prenatal genetic testing for fetuses with morphological abnormalities but normal rapid aneuploidy detection and microarray analysis. We present a retrospective study of 90 fetuses with different abnormal ultrasound findings, in which we employed the singleton exome sequencing (sES; 75 fetuses) or to a lesser extent (15 fetuses) a multigene panel analysis of 6713 genes as a primary tool for the detection of monogenic diseases. The detection rate of pathogenic or likely pathogenic variants in this study was 34.4%. The highest diagnostic rate of 56% was in fetuses with multiple anomalies, followed by cases with skeletal or renal abnormalities (diagnostic rate of 50%, respectively). We report 20 novel disease-causing variants in different known disease-associated genes and new genotype–phenotype associations for the genes KMT2D, MN1, CDK10, and EXOC3L2. Based on our data, we postulate that sES of fetal index cases with a concurrent sampling of parental probes for targeted testing of the origin of detected fetal variants could be a suitable tool to obtain reliable and rapid prenatal results, particularly in situations where a trio analysis is not possible.

Risk of Secondary Household Transmission of COVID-19 from Health Care Workers in a Hospital in Spain

Background: Hospital health care workers are at high risk of developing COVID-19 and transmitting the disease to their family upon returning home; the aim here is to estimate the secondary attack rate of COVID-19 in household contacts of health care workers and their transmission risk factors. Material and Methods: COVID-19 cases in the health care workers of an academic hospital in Pamplona, Spain, from 2 March to 26 May 2020, were followed up. The secondary attack rate (SAR) was estimated from cases in household contacts of index cases and their risk factors by Poisson regression. Results: 89 index cases were studied from 99 notified cases in health care workers (89.0%), excluding secondary cases or those who lived alone. Forty-six secondary cases confirmed by the laboratory were found among 326 household contacts, a secondary attack rate of 14.11% (95% CI 10.75–18.31), and 33 household contacts with acute infection symptoms without microbiologic confirmation 10.12% (95% CI 7.30–13.87). Considering all the cases, the secondary attack rate was 27.3 (95% CI 22.75–32.38). Risk factors were the gender and profession of the index case, the number of people living in the household, and the number of persons per bedroom. When the index case health worker used a single room, it had a protective effect, with an incidence rate ratio (IRR) of 0.493 (95% CI 0.246–0.985); Conclusions: The secondary attack rate found among household contacts of health care workers is high. The preventive isolation of health care workers in individual rooms in their house may reduce the transmission in their families.

Impact of Changes in Infection Control Measures on the Dynamics of COVID-19 Infections in Schools and Pre-schools

Introduction: With the increased emergence of SARS-CoV-2 variants, the impact on schools and preschools remains a matter of debate. To ensure that schools and preschools are kept open safely, the identification of factors influencing the extent of outbreaks is of importance.Aim: To monitor dynamics of COVID-19 infections in schools and preschools and identify factors influencing the extent of outbreaks.Methods: In this prospective observational study we analyzed routine surveillance data of Mecklenburg-Western Pomerania, Germany, from calendar week (CW) 32, 2020 to CW19, 2021 regarding SARS-CoV-2 infection events in schools and preschools considering changes in infection control measures over time. A multivariate linear regression model was fitted to evaluate factors influencing the number of students, teachers and staff tested positive following index cases in schools and preschools. Due to an existing multicollinearity in the common multivariate regression model between the variables “face mask obligation for children” and “face mask obligation for adults”, two further separate regression models were set up (Multivariate Model Adults and Multivariate Model Children).Results: We observed a significant increase in secondary cases in preschools in the first quarter of 2021 (CW8 to CW15, 2021), and simultaneously a decrease in secondary cases in schools. In multivariate regression analysis, the strongest predictor of the extent of the outbreaks was the teacher/ caregiver mask obligation (B = −1.9; 95% CI: −2.9 to −1.0; p < 0.001). Furthermore, adult index cases (adult only or child+adult combinations) increased the likelihood of secondary cases (B = 1.3; 95% CI: 0.9 to 1.8; p < 0.001). The face mask obligation for children also showed a significant reduction in the number of secondary cases (B = −0.6; 95% CI: −0.9 to −0.2; p = 0.004.Conclusion: The present study indicates that outbreak events at schools and preschools are effectively contained by an obligation for adults and children to wear face masks.

Comprehensive Contact Tracing, Testing and Sequencing Show Limited Transmission of SARS-CoV-2 between Children in Schools in Norway, August 2020 to May 2021

The role of children in the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in schools has been a topic of controversy. In this study among school contacts of SARS-CoV-2 positive children in 43 contact-investigations, we investigated SARS-CoV-2 transmission in Norway, August 2020–May 2021. All participants were tested twice within seven to ten days, using SARS-CoV-2 PCR on home-sampled saliva. Positive samples were whole genome sequenced. Among the 559 child contacts, eight tested positive (1.4%, 95% CI 0.62–2.80), with no significant difference between primary (1.0%, 95% CI 0.27–2.53) and secondary schools (2.6%, 95% CI 0.70–6.39), p = 0.229, nor by viral strain, non-Alpha (1.4%, 95% CI 0.50–2.94) and Alpha variant (B.1.1.7) (1.7%, 95% CI 0.21–5.99), p = 0.665. One adult contact (1/100) tested positive. In 34 index cases, we detected 13 different SARS-CoV-2 Pango lineage variants, with B.1.1.7 being most frequent. In the eight contact-investigations with SARS-CoV-2 positive contacts, four had the same sequence identity as the index, one had no relation, and three were inconclusive. With mitigation measures in place, the spread of SARS-CoV-2 from children in schools is limited. By excluding contact-investigations with adult cases known at the time of enrolment, our data provide a valid estimate on the role of children in the transmission of SARS-CoV-2 in schools.

COVID-19 clusters in schools: frequency, size, and transmission rates from crowdsourced exposure reports

The role of schools in the spread of the COVID-19 pandemic is controversial, with some claiming they are an important driver of the pandemic and others arguing that transmission in schools is negligible. School cluster reports that have been collected in various jurisdictions are a source of data about transmission in schools. These reports consist of the name of a school, a date, and the number of students known to be infected. We provide a simple model for the frequency and size of clusters in this data, based on random arrivals of index cases at schools who then infect their classmates with a highly variable rate, fitting the overdispersion evident in the data. We fit our model to reports for several jurisdictions in the US and Canada, providing estimates of mean and dispersion for cluster size, whilst factoring in imperfect ascertainment. Our parameter estimates are robust to variations in ascertainment fraction. We use these estimates in three ways: i) to explore how uneven the distribution of cases is among different clusters in different jurisdictions (that is, what fraction of cases are in the 20% largest clusters), ii) to estimate how long it will be until we see a cluster a given size in jurisdiction, and iii) to determine the distribution of instantaneous transmission rate β among different index case. We show how these latter distribution can be used in simulations of school transmission where we explore the effect of different interventions, in the context of highly variable transmission rates.

Demographic, Clinical and Radiological Features of Healthcare Workers and Two Index Cases That Were Infected with COVID-19 (SARS-Cov-2)

To evaluate the index cases leading to the transmission of healthcare workers (HCWs) in Rize/Turkey Recep Tayyip Erdogan University Faculty of Medicine Education and Research Hospital with COVID-19 infection and the clinical features of infected HCWs. The first two COVID-19 test positive patients treated at Rize/Turkey between 10.03.2020 and 12.04.2020 and HCWs those who examined these two patients whose COVID-19 PCR test results were positive were included in this study. In Rize/Turkey, the first and second cases of positive COVID-19 which was recorded on 13.03.2020 on 25.03.2020, 27 HCWs (female, 63%, n = 17 and male, 37%, n = 10 and the mean age was 33.2 ± 6.9 years) who contacted during the treatment of these cases and became COVID-19 positive were examined. The median of symptom duration (days) of the HCWs was 5 days (range: 0–17 days). Fever, 55.6% (n = 15); malaise, 44.4% (n = 12); cough, 40.7% (n = 11); sore throat, 33.3% (n = 9); myalgia, 33.3% (n = 9); dyspnea, 14.8% (n = 4); diarrhea, 22.2% (n = 6); vomiting, 14.8% (n = 4); anosmia, 18.5% (n = 5); ageusia, 22.2% (n = 6) and headache, 37% (n = 10) of the cases. The rates of headache in female HCWs infected with COVID-19 were found to be significantly higher compared to men (52.9%). None of them had severe clinical situation requiring intensive care follow-up or acute respiratory distress syndrome (ARDS). Laboratory measurements of HCWs were carried out at the first when they had symptoms and when they recovered, and results were compared accordingly. The thorax computerized tomography (CT) findings of HCWs were normal in 74.1% (n = 20) of total. HCWs were initially affected by the COVID-19 pandemic. Early measures provided by the Health authorities, access to diagnosis and treatment, and the young age average in HCWs prevented severe outcomes such as severe clinical course and mortality at the beginning of the outbreak.

30 year experience of index case identification and outcomes of cascade testing in high-risk breast and colorectal cancer predisposition genes

It is 30 years since the first diagnostic cancer predisposition gene (CPG) test in the Manchester Centre for Genomic Medicine (MCGM), providing opportunities for cancer prevention, early detection and targeted treatments in index cases and at-risk family members. Here, we present time trends (1990–2020) of identification of index cases with a germline CPG variant and numbers of subsequent cascade tests, for 15 high-risk breast and gastro-intestinal tract cancer-associated CPGs: BRCA1, BRCA2, PALB2, PTEN, TP53, APC, BMPR1a, CDH1, MLH1, MSH2, MSH6, PMS2, SMAD4, STK11 and MUTYH. We recorded 2082 positive index case diagnostic screening tests, generating 3216 positive and 3140 negative family cascade (non-index) tests. This is equivalent to an average of 3.05 subsequent cascade tests per positive diagnostic index test, with 1.54 positive and 1.51 negative non-index tests per family. The CPGs with the highest numbers of non-index positive cases identified on cascade testing were BRCA1/2 (n = 1999) and the mismatch repair CPGs associated with Lynch Syndrome (n = 731). These data are important for service provision and health economic assessment of CPG diagnostic testing, in terms of cancer prevention and early detection strategies, and identifying those likely to benefit from targeted treatment strategies.

Surge in SARS-CoV-2 transmission in school-aged children and household contacts, England, August to October 2021

Easing of COVID-19 restrictions in England in the summer of 2021 was followed by a sharp rise in cases among school-aged children. Weekly rates of SARS-CoV-2 infection in primary and secondary school children reached 733.3 and 1,664.7/100,000 population, respectively, by week 39 2021. A surge in household clusters with school-aged index cases was noted at the start of the school term, with secondary cases predominantly in children aged 5–15 years and adults aged 30–49 years.

Risk factors associated with malaria infection identified through reactive case detection in Zanzibar, 2012–2019

Background Over the past two decades, Zanzibar substantially reduced malaria burden. As malaria decreases, sustainable improvements in control interventions may increasingly depend on accurate knowledge of malaria risk factors to further target interventions. This study aimed to investigate the risk factors associated with malaria infection in Zanzibar. Methods Surveillance data from Zanzibar’s Malaria Case Notification system from August 2012 and December 2019 were analyzed. This system collects data on malaria cases passively detected and reported by all health facilities (index cases), and household-based reactive case detection (RCD) activities linked to those primary cases. All members of households of the index cases were screened for malaria using a malaria rapid diagnostic test (RDT). Individuals with a positive RDT were treated with artemisinin-based combination therapy. Univariate and multivariate logistic regression analyses were done to investigate the association between RDT positivity among the household members and explanatory factors with adjustment for seasonality and clustering at Shehia level. Results A total of 30,647 cases were reported of whom household RCD was completed for 21,443 (63%) index case households and 85,318 household members tested for malaria. The findings show that younger age (p-value for trend [Ptrend] < 0.001), history of fever in the last 2 weeks (odds ratio [OR] = 35.7; 95% CI 32.3–39.5), travel outside Zanzibar in the last 30 days (OR = 2.5; 95% CI 2.3–2.8) and living in Unguja (OR = 1.2; 95% CI 1.0–1.5) were independently associated with increased odds of RDT positivity. In contrast, male gender (OR=0.8; 95% CI 0.7–0.9), sleeping under an LLIN the previous night (OR = 0.9; 95% CI 0.7–0.9), having higher household net access (Ptrend < 0.001), and living in a household that received IRS in the last 12 months (OR = 0.8; 95% CI 0.7–0.9) were independently associated with reduced odds of RDT positivity. A significant effect modification of combining IRS and LLIN was also noted (OR = 0.7; 95% CI 0.6–0.8). Conclusions The findings suggest that vector control remains an important malaria prevention intervention: they underscore the need to maintain universal access to LLINs, the persistent promotion of LLIN use, and application of IRS. Additionally, enhanced behavioural change and preventive strategies targeting children aged 5–14 years and travellers are needed.