Assessment and comparison of the ILI case definition in clinical and school-based community settings: ORCHARDS/IISP.

Context: Influenza-like illness (ILI) is commonly used in clinical and public health settings to identify influenza cases. CDC defines ILI as fever and either cough or sore throat, with symptom onset within 7 days. Objective: Assess performance of ILI criteria in two settings (clinical and community), comparing symptom profiles and laboratory detection of influenza in children. Study Design and Analysis: Retrospective analyses of data from medically attended influenza (MAI) surveillance and a communitybased study. Datasets were analyzed separately to assess predictors of influenza cases. Analyses were limited to specimens collected within 7 days of symptom onset. Relationships between influenza and each categorical variable were described by the confusion matrix, sensitivity, and specificity. Associations were tested using chi-square tests. Unadjusted and adjusted logistic regression models were used for all variables with RT-PCR result as the outcome. Setting or Dataset: The ORegon CHild Absenteeism due to Respiratory Disease Study (ORCHARDS) is a respiratory infection study based in the Oregon School District (Dane County, WI). The Wisconsin Influenza Incidence Surveillance Project (IISP) is a MAI surveillance system operating in five family medicine clinics in Dane County. Population Studied: Children aged 4-18 years with acute respiratory infections. Intervention/Instrument: Oropharyngeal specimens, collected by research staff (ORCHARDS) or clinicians (IISP), were tested for influenza via RT-PCR and for multiple respiratory viruses at the Wisconsin State Laboratory of Hygiene. Extensive demographic and symptoms data were collected from all participants. Outcome Measures: Influenza(+)PCR. Results: From 9/7/2010-3/12/2020, 1,338 and 2,359 specimens meeting inclusion criteria were collected for IISP and ORCHARDS, respectively. Cough, fever, and ILI classification were significantly associated with influenza (sensitivity ≥92.8%, ≥85.9%, and ≥84.5%, respectively). Receiver operator curve analysis confirmed ILI had high predictive ability in both settings, improved by the inclusion of seasonality and influenza vaccination status (IISP: 0.61 vs 0.76, ORCHARDS: 0.68 vs 0.78). Conclusions: ILI performed well in both clinical and community contexts. Factors most highly associated with increased odds of RT-PCR(+) results were cough, fever, and ILI. Inclusion of seasonality and influenza vaccination status improved the predictive value of ILI in both datasets.

Changing pattern of respiratory virus detections among school-aged children in a small community - Dane County, Wisconsin, September to December 2022.

Widespread school closures and other non-pharmaceutical interventions (NPIs), used to limit the spread of SARS-CoV-2, significantly disrupted transmission patterns of seasonal respiratory viruses. As NPIs were relaxed, populations were vulnerable to resurgence. This study within a small community assessed acute respiratory illness among kindergarten through grade 12 students as they returned to public schools from September through December 2022 without masking and distancing requirements. The 277 specimens collected demonstrated a shift from rhinovirus to influenza. With continued circulation of SARS-CoV-2 and return of seasonal respiratory viruses, understanding evolving transmission patterns will play an important role in reducing disease burden.

Assessment of potential factors associated with the sensitivity and specificity of Sofia Influenza A+B Fluorescent Immunoassay in an ambulatory care setting.

BACKGROUND: Seasonal influenza leads to an increase in outpatient clinic visits. Timely, accurate, and affordable testing could facilitate improved treatment outcomes. Rapid influenza diagnostic tests (RIDTs) provide results in as little as 15 minutes and are relatively inexpensive, but have reduced sensitivity when compared to RT-PCR. The contributions of multiple factors related to test performance are not well defined for ambulatory care settings. We assessed clinical and laboratory factors that may affect the sensitivity and specificity of Sofia Influenza A+B Fluorescence Immunoassay. STUDY DESIGN: We performed a post-hoc assessment of surveillance data amassed over seven years from five primary care clinics. We analyzed 4,475 paired RIDT and RT-PCR results from specimens collected from patients presenting with respiratory symptoms and examined eleven potential factors with additional sub-categories that could affect RIDT sensitivity. RESULTS: In an unadjusted analysis, greater sensitivity was associated with the presence of an influenza-like illness (ILI), no other virus detected, no seasonal influenza vaccination, younger age, lower cycle threshold value, fewer days since illness onset, nasal discharge, stuffy nose, and fever. After adjustment, presence of an ILI, younger age, fewer days from onset, no co-detection, and presence of a nasal discharge maintained significance. CONCLUSION: Clinical and laboratory factors may affect RIDT sensitivity. Identifying potential factors during point-of-care testing could aid clinicians in appropriately interpreting negative influenza RIDT results.

An assessment of parental knowledge, attitudes, and beliefs regarding influenza vaccination.

INTRODUCTION: Seasonal influenza imposes a significant clinical and economic burden. Despite the availability of an annual vaccine to prevent influenza infection and reduce disease severity, influenza vaccination rates remain suboptimal. Research suggests personal experience, perceived effectiveness, and concerns regarding vaccine safety and side effects are the most influential factors in predicting a parent's decision to vaccinate. However, current literature is primarily focused on the vaccine decision-making of healthcare workers and those at high risk for influenza complications. METHODS: To assess parental attitudes and beliefs regarding the influenza vaccine, a brief mixed-methods survey was developed and optimized for an electronic platform. The Health Belief Model informed survey design and data analysis. Questions were classified into five core concepts: knowledge, barriers, benefits, experience, and severity. Participants were solicited from a population of parents whose children had participated in a school-based influenza surveillance study (n = 244, 73% response rate). We tested associations between responses and children's influenza vaccination status the prior season. Categorical questions were tested using Pearson's chi-squared tests and numerical or ordered questions using Mann-Whitney tests. P-values were corrected using the Bonferroni method. RESULTS: Doubting effectiveness, concerns about side effects, inconvenience, and believing the vaccine is unnecessary were barriers negatively associated with parents' decision to vaccinate their children during the 2017-18 flu season (p < 0.001). Knowledge that the vaccine is effective in lowering risk, duration, and severity of influenza; receiving the influenza vaccine as an adult; and recognizing the importance of vaccination to prevent influenza transmission in high-risk populations were positively associated with parents' decision to vaccinate (p < 0.001). CONCLUSION: Understanding barriers and motivators behind parents' decision to vaccinate provides valuable insight that has the potential to shape vaccine messaging, recommendations, and policy. The motivation to vaccinate to prevent influenza transmission in high-risk populations is a novel finding that warrants further investigation.