Household Transmission Dynamics of Seasonal Human Coronaviruses.

BACKGROUND: Household transmission studies inform how viruses spread among close contacts, but few characterize household transmission of endemic coronaviruses. METHODS: We used data collected from 223 households with school-age children participating in weekly disease surveillance over 2 respiratory virus seasons (December 2015 to May 2017), to describe clinical characteristics of endemic human coronaviruses (HCoV-229E, HcoV-HKU1, HcoV-NL63, HcoV-OC43) infections, and community and household transmission probabilities using a chain-binomial model correcting for missing data from untested households. RESULTS: Among 947 participants in 223 households, we observed 121 infections during the study, most commonly subtype HCoV-OC43. Higher proportions of infected children (<19 years) displayed influenza-like illness symptoms than infected adults (relative risk, 3.0; 95% credible interval [CrI], 1.5-6.9). The estimated weekly household transmission probability was 9% (95% CrI, 6-13) and weekly community acquisition probability was 7% (95% CrI, 5-10). We found no evidence for differences in community or household transmission probabilities by age or symptom status. Simulations suggest that our study was underpowered to detect such differences. CONCLUSIONS: Our study highlights the need for large household studies to inform household transmission, the challenges in estimating household transmission probabilities from asymptomatic individuals, and implications for controlling endemic CoVs.

Predicting virologically confirmed influenza using school absences in Allegheny County, Pennsylvania, USA during the 2007-2015 influenza seasons.

BACKGROUND: Children are important in community-level influenza transmission. School-based monitoring may inform influenza surveillance. METHODS: We used reported weekly confirmed influenza in Allegheny County during the 2007 and 2010-2015 influenza seasons using Pennsylvania's Allegheny County Health Department all-age influenza cases from health facilities, and all-cause and influenza-like illness (ILI)-specific absences from nine county school districts. Negative binomial regression predicted influenza cases using all-cause and illness-specific absence rates, calendar week, average weekly temperature, and relative humidity, using four cross-validations. RESULTS: School districts reported 2 184 220 all-cause absences (2010-2015). Three one-season studies reported 19 577 all-cause and 3012 ILI-related absences (2007, 2012, 2015). Over seven seasons, 11 946 confirmed influenza cases were reported. Absences improved seasonal model fits and predictions. Multivariate models using elementary school absences outperformed middle and high school models (relative mean absolute error (relMAE) = 0.94, 0.98, 0.99). K-5 grade-specific absence models had lowest mean absolute errors (MAE) in cross-validations. ILI-specific absences performed marginally better than all-cause absences in two years, adjusting for other covariates, but markedly worse one year. CONCLUSIONS: Our findings suggest seasonal models including K-5th grade absences predict all-age-confirmed influenza and may serve as a useful surveillance tool.

Influenza and other respiratory viral infections associated with absence from school among schoolchildren in Pittsburgh, Pennsylvania, USA: a cohort study.

BACKGROUND: Information on the etiology and age-specific burden of respiratory viral infections among school-aged children remains limited. Though school aged children are often recognized as driving the transmission of influenza as well as other respiratory viruses, little detailed information is available on the distribution of respiratory infections among children of different ages within this group. Factors other than age including gender and time spent in school may also be important in determining risk of infection but have been little studied in this age group. METHODS: We conducted a cohort study to determine the etiology of influenza like illness (ILI) among 2519 K-12 students during the 2012-13 influenza season. We obtained nasal swabs from students with ILI-related absences. Generalized linear mixed-effect regressions determined associations of outcomes, including ILI and laboratory-confirmed respiratory virus infection, with school grade and other covariates. RESULTS: Overall, 459 swabs were obtained from 552 ILI-related absences. Respiratory viruses were found in 292 (63.6%) samples. Influenza was found in 189 (41.2%) samples. With influenza B found in 134 (70.9%). Rates of influenza B were significantly higher in grades 1 (10.1, 95% CI 6.8-14.4%), 2 (9.7, 6.6-13.6%), 3 (9.3, 6.3-13.2%), and 4 (9.9, 6.8-13.8%) than in kindergarteners (3.2, 1.5-6.0%). After accounting for grade, sex and self-reported vaccination status, influenza B infection risk was lower among kindergarteners in half-day programs compared to kindergarteners in full-day programs (OR = 0.19; 95% CI 0.08-0.45). CONCLUSIONS: ILI and influenza infection is concentrated in younger schoolchildren. Reduced infection by respiratory viruses is associated with a truncated school day for kindergarteners but this finding requires further investigation in other grades and populations.

Age-specific social mixing of school-aged children in a US setting using proximity detecting sensors and contact surveys.

Comparisons of the utility and accuracy of methods for measuring social interactions relevant to disease transmission are rare. To increase the evidence base supporting specific methods to measure social interaction, we compared data from self-reported contact surveys and wearable proximity sensors from a cohort of schoolchildren in the Pittsburgh metropolitan area. Although the number and type of contacts recorded by each participant differed between the two methods, we found good correspondence between the two methods in aggregate measures of age-specific interactions. Fewer, but longer, contacts were reported in surveys, relative to the generally short proximal interactions captured by wearable sensors. When adjusted for expectations of proportionate mixing, though, the two methods produced highly similar, assortative age-mixing matrices. These aggregate mixing matrices, when used in simulation, resulted in similar estimates of risk of infection by age. While proximity sensors and survey methods may not be interchangeable for capturing individual contacts, they can generate highly correlated data on age-specific mixing patterns relevant to the dynamics of respiratory virus transmission.

Age-specific social mixing of school-aged children in a US setting using proximity detecting sensors and contact surveys.

Comparisons of the utility and accuracy of methods for measuring social interactions relevant to disease transmission are rare. To increase the evidence base supporting specific methods to measure social interaction, we compared data from self-reported contact surveys and wearable proximity sensors from a cohort of schoolchildren in the Pittsburgh metropolitan area. Although the number and type of contacts recorded by each participant differed between the two methods, we found good correspondence between the two methods in aggregate measures of age-specific interactions. Fewer, but longer, contacts were reported in surveys, relative to the generally short proximal interactions captured by wearable sensors. When adjusted for expectations of proportionate mixing, though, the two methods produced highly similar, assortative age-mixing matrices. These aggregate mixing matrices, when used in simulation, resulted in similar estimates of risk of infection by age. While proximity sensors and survey methods may not be interchangeable for capturing individual contacts, they can generate highly correlated data on age-specific mixing patterns relevant to the dynamics of respiratory virus transmission.

Social Contact Networks and Mixing among Students in K-12 Schools in Pittsburgh, PA.

Students attending schools play an important role in the transmission of influenza. In this study, we present a social network analysis of contacts among 1,828 students in eight different schools in urban and suburban areas in and near Pittsburgh, Pennsylvania, United States of America, including elementary, elementary-middle, middle, and high schools. We collected social contact information of students who wore wireless sensor devices that regularly recorded other devices if they are within a distance of 3 meters. We analyzed these networks to identify patterns of proximal student interactions in different classes and grades, to describe community structure within the schools, and to assess the impact of the physical environment of schools on proximal contacts. In the elementary and middle schools, we observed a high number of intra-grade and intra-classroom contacts and a relatively low number of inter-grade contacts. However, in high schools, contact networks were well connected and mixed across grades. High modularity of lower grades suggests that assumptions of homogeneous mixing in epidemic models may be inappropriate; whereas lower modularity in high schools suggests that homogenous mixing assumptions may be more acceptable in these settings. The results suggest that interventions targeting subsets of classrooms may work better in elementary schools than high schools. Our work presents quantitative measures of age-specific, school-based contacts that can be used as the basis for constructing models of the transmission of infections in schools.

Household transmission of influenza A and B in a school-based study of non-pharmaceutical interventions.

The effect of school-based non-pharmaceutical interventions (NPIs) on influenza A and B transmission in children's households has not been estimated in published literature. We use data from a large school-based cluster randomized trial of improved hand and respiratory hygiene measures to explore the secondary transmission of influenza A and B in households of laboratory confirmed influenza cases. Data were taken from the Pittsburgh Influenza Prevention Project, a cluster-randomized trial of NPIs conducted in ten Pittsburgh, PA elementary schools during the 2007-2008 influenza season. We estimated two measures of influenza transmissibility in households; the susceptible infectious transmission probability, using variants of the Reed-Frost chain binomial model, and the secondary attack rate. We identified predictors of ILI using a logistic generalized estimating equation model. We estimate the secondary attack rates in intervention households to be 0.26 (95% confidence interval (CI) 0.19-0.34) compared to 0.30 (95% CI 0.23-0.38) in control households. Race and age were significant risk factors for secondary ILI acquisition in this study. We found no significant differences between the transmission probabilities for infectious individuals in intervention (0.19, 95% CI 0.14-0.25), and control households (0.22, 95% CI 0.16-0.29). Similarly, estimates for secondary attack rates and transmission probabilities for households with confirmed influenza A (0.31 and 0.22) were not significantly different from estimates from households with confirmed influenza B (0.25 and 0.20). While influenza A and B are thought to have different transmission characteristics, we find no significant differences in their transmissibility within households. Though our results suggest a potential effect, we found no statistically significant effect of school-based non-pharmaceutical interventions on transmission in symptomatic children's homes.

Public Health Area of Concentration: a model for integration into medical school curricula.

Calls for more public health education for medical students date back at least 150 years. In recent years, medical schools have increased their required coursework in core public health topics such as epidemiology, biostatistics, and behavioral determinants of health. Some schools have created more in-depth alternatives, including combined or concurrent master's degrees; MD/PhD programs with a public health track; certificates in public health; or complete re-envisioning of the school into an integrated medical and public health institution. In 2009 the University of Pittsburgh School of Medicine began a Public Health Area of Concentration (AOC) that provides an optional, integrated curriculum that includes key elements of research, practice, and leadership. The AOC is a partnership between two schools at the University of Pittsburgh--Medicine and Public Health--and the local county health department. The result is a program that provides mentorship and training over 4 years of education designed to mend the long historical divide between the skills and constituencies of individual and population health. In addition, the AOC is relatively easy and inexpensive to implement and is modular in nature. The Public Health AOC is a simple model for incorporating many key aspects of public health into medical education and can be duplicated by any university that is willing to create partnerships and work across boundaries.

Sensitivity and specificity of rapid influenza testing of children in a community setting.

INTRODUCTION: Rapid influenza testing (RFT) allows for a rapid point-of-care diagnosis of influenza. The Quidel QuickVue Influenza A+B test (QuickVue) has a reported manufacturer's sensitivity and specificity of 73% and 96%, respectively, with nasal swabs. However, investigators have shown sensitivities ranging from 22% to 77% in community settings. METHODS: The QuickVue rapid influenza test was evaluated in a population of elementary (K-5) school children, using testing in the home, as part of the Pittsburgh Influenza Prevention Project during the 2007-2008 influenza season. The QuickVue test was performed with nasal swab in full accordance with package instructions and compared with the results of nasal swab semi-quantitative RT-PCR. RESULTS: Sensitivity of the QuickVue was found to be 27% in this sample. There was no statistically valid correlation between the semi-quantitative PCR result and the QuickVue result. CONCLUSIONS: This study is consistent with the low sensitivity of the QuickVue test also reported by others. Viral load, technique, and the use of nasal swabs were examined as contributing factors but were not found to be explanations for this result. Community testing includes patients who are on the lower spectrum of illness which would not be the case in hospital or clinic samples. This suggests that RFT is less sensitive for patients at the lower spectrum of illness, with less severe disease.

The effect of grade on compliance using nonpharmaceutical interventions to reduce influenza in an urban elementary school setting.

OBJECTIVES: The Pittsburgh Influenza Prevention Project (PIPP) has previously shown that school-aged children in grades K-5 can learn hygiene-based, nonpharmaceutical interventions (NPIs) and persist in these behaviors over the duration of an influenza season. The purpose of this study was to determine whether age (as estimated by grade) plays any role in this ability. METHODS: The Pittsburgh Influenza Prevention Project is a prospective, controlled, randomized trial of the effectiveness of a suite of NPIs in 10 elementary schools. The project measured adoption of NPIs by students through surveys of intervention homeroom teachers before, during, and after the influenza season and control home-room teachers after influenza season. RESULTS: There were large, statistically significant improvements and persistence over time across all grade levels, in students' concern about influenza and their daily practice of NPIs that promote health behaviors-"wash or sanitize your hands often" and "cover your coughs and sneezes." Nonpharmaceutical interventions characterized as extinguishing unhealthy behaviors, such as "avoid touching your eyes, nose, and mouth" or "home is where you stay when you are sick," showed no reliable improvement. CONCLUSIONS: The study provides evidence that elementary school-aged children, across all grades, can understand and implement protective NPIs and maintain these activities throughout influenza season and beyond. Improvements were most prominent when teaching students to engage in health-promoting behaviors. Habitual behaviors (unconscious touching) and changing family behaviors (staying home) seem less susceptible to intervention. These results will be useful to public health policy makers and health care practitioners considering methods of infectious disease prevention in school-based settings.

Compliance with a multilayered nonpharmaceutical intervention in an urban elementary school setting.

OBJECTIVES: The purpose of this study was to determine to what extent school-aged children can learn hygiene-based nonpharmaceutical interventions (NPIs) and persist in these behavioral changes over the duration of an influenza season. If this can be done successfully, it may be a preferable pandemic mitigation strategy to much more disruptive strategies such as whole-scale school closure. METHODS: The Pittsburgh Influenza Prevention Project (PIPP) is a prospective, controlled, randomized trial of the effectiveness of a suite of hygiene-based NPIs in controlling influenza and related illnesses in elementary schools in the City of Pittsburgh. During the 2007-08 school year, the project measured adoption of NPIs by students in five elementary schools through surveys of home-room teachers before, during, and after influenza season. RESULTS: Results showed highly statistically significant improvement in students' daily practice of nearly all of the NPIs, including hand washing and sanitizer use and covering coughs and sneezes. CONCLUSIONS: The study provides evidence that children can learn, implement, and persist in the behaviors of a multilayered suite of NPIs over a typical flu season. These results will be useful to public health policy makers and practitioners considering methods of infectious disease prevention in school-based settings.

Research findings from nonpharmaceutical intervention studies for pandemic influenza and current gaps in the research.

In June 2006, the Centers for Disease Control and Prevention released a request for applications to identify, improve, and evaluate the effectiveness of nonpharmaceutical interventions (NPIs)-strategies other than vaccines and antiviral medications-to mitigate the spread of pandemic influenza within communities and across international borders (RFA-CI06-010). These studies have provided major contributions to seasonal and pandemic influenza knowledge. Nonetheless, key concerns were identified related to the acceptability and protective efficacy of NPIs. Large-scale intervention studies conducted over multiple influenza epidemics, as well as smaller studies in controlled laboratory settings, are needed to address the gaps in the research on transmission and mitigation of influenza in the community setting. The current novel influenza A (H1N1) pandemic underscores the importance of influenza research.

Preserving lessons learned in disease outbreaks and other emergency responses.

BACKGROUND: Public health departments often miss the opportunity to both learn from outbreaks and disasters and share any 'lessons learned' with other public health partners. These missed opportunities inhibit the public health system's ability to improve, change and adapt in an organized way. METHODS: In 2003, Western Pennsylvania experienced the largest documented hepatitis A outbreak in US history. The authors documented the key facets of both the outbreak and the response, and in the process developed improved methods for capturing the historical record in an efficient and comprehensive fashion. This process incorporates key aspects of oral history, along with typical public health parameters such as epidemic curves and environmental risk factors, and allows for creation of unique tools for documentation and sharing with diverse audiences. CONCLUSIONS: Learning from experience is an essential part of reducing mistakes, improving public health response, and the methods described herein show one way that 'lessons learned' can become a valuable teaching/training tool for students and practitioners.

Low sensitivity of rapid diagnostic test for influenza.

The QuickVue Influenza A+B Test (Quidel) was used to test nasal swab specimens obtained from persons with influenza-like illness in 3 different populations. Compared with reverse-transcriptase polymerase chain reaction, the test sensitivity was low for all populations (median, 27%; range, 19%-32%), whereas the specificity was high (median, 97%; range, 96%-99.6%).

Using nonpharmaceutical interventions to prevent influenza transmission in elementary school children: parent and teacher perspectives.

OBJECTIVES: Schools act as "amplifying sites" for the spread of infectious diseases, outbreaks, and pandemics. This project assessed which nonpharmaceutical interventions (NPIs) are most acceptable to parents and teachers of school children in grades K-5 to K-8 in Pittsburgh public schools. METHODS: During the spring of 2007, the Pittsburgh Influenza Prevention Project surveyed 134 teachers and 151 parents representing nine elementary schools regarding attitudes toward NPIs and their usage by adults and school children during seasonal influenza outbreaks. RESULTS: General etiquette practices such as covering coughs, handwashing, and using hand sanitizer were highly acceptable to both groups, while masks and gloves were not. CONCLUSIONS: The success of an NPI or a set of NPIs depends on both its efficacy and the feasibility of implementing it with relevant populations. If masks, gloves, and other more intrusive NPIs are to be used in community settings during a severe influenza season or pandemic, it is clear that there is significant preparatory work needed to increase acceptability on the part of the adults. Without such acceptance, it is highly unlikely that children and their supervising adults will participate.