Respiratory Virus Research Articles

Respiratory Viral Co-infection in SARS-CoV-2-Infected Children During the Early and Late Pandemic Periods

Background: Knowledge regarding the impact of respiratory pathogen co-infection in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected children seeking emergency department care is limited, specifically as it relates to the association between SARS-CoV-2 viral co-infection and disease severity and factors associated with co-infection. Methods: This secondary analysis included data from 2 prospective cohort studies conducted between March 2020 and February 2022 that included children <18 years of age tested for SARS-CoV-2 infection along with additional respiratory viruses in a participating emergency department. Outcomes included the detection rate of other respiratory viruses and the occurrence of severe outcomes (ie, intensive interventions, severe organ impairment and death). Results: We included 2520 participants, of whom 388 (15.4%) were SARS-CoV-2-positive. Detection of additional respiratory viruses occurred in 18.3% (71/388) of SARS-CoV-2-positive children, with rhinovirus/enterovirus being most frequently detected (42/388; 10.8%). In multivariable analyses (adjusted odds ratio and 95% confidence interval), among SARS-CoV-2-positive children, detection of another respiratory virus was not associated with severe outcomes [1.74 (0.80–3.79)], but detection of rhinovirus/enterovirus [vs. isolated SARS-CoV-2 detection 3.56 (1.49–8.51)] and having any preexisting chronic medical condition [2.15 (1.06–4.36)] were associated with severe outcomes. Among SARS-CoV-2-positive children, characteristics independently associated with an increased odds of any other viral co-infection included: age and delta variant infection. Conclusions: Approximately 1 in 5 children infected with SARS-CoV-2 had co-infection with another respiratory virus, and co-infection with rhinovirus/enterovirus was associated with severe outcomes. When public health restrictions were relaxed, co-infections increased.

The Prevalence, Serogroup Distribution and Risk Factors of Meningococcal Carriage in Children, Adolescents and Young Adults in Turkey Meningo-Carr-TR Study PART 3: COVID-19 Pandemic Situation

Background: The prevalence of meningococcal carriage and serogroup distribution is crucial for assessing the epidemiology of invasive meningococcal disease, forecasting outbreaks and formulating potential immunization strategies. Following the meningococcal carriage studies conducted in Turkey in 2016 and 2018, we planned to re-evaluate meningococcal carriage in children, adolescents and young adults during the COVID-19 pandemic period. Methods: In the MENINGO-CARR-3 study, we collected nasopharyngeal samples from 1585 participants 0–24 years of age, across 9 different centers in Turkey. We used polymerase chain reaction and serogroup distribution to determine how common it is for people to carry Neisseria meningitidis. Results: The overall meningococcal carriage rate was 8.5% (n = 134). The serogroup distribution was as follows: serogroup A, 6%; serogroup B, 30.6%; serogroup W, 12.7%; serogroup Y, 3.7%; serogroup X, 1.5% and nongroupable as 45.5%. The highest carriage rate was found in 15–17-year-old adolescents (24.1%, 17.9%, and 20.2%, respectively). The carriage rate was higher among participants who had a previous COVID-19 infection (P = 0.05; odds ratio: 1.95; 95% confidence interval: 1.11–3.44). The nasopharyngeal carriage rate was also higher than in the 2016 and 2018 studies (8.45% vs. 6.3% and 7.5%, respectively), and the most prevalent groupable serogroup was B during this study period, followed by serogroup W in 2016 and serogroup X in 2018. Conclusions: The present study found that meningococcal carriage was higher during the post-COVID-19 pandemic period, especially in adolescents and young adults. Severe acute respiratory syndrome coronavirus-2 virus itself and/or pandemic mitigation strategies may affect both meningococcal carriage and serogroup distribution. Serogroup distribution varies between years, and further immunization strategies, including adolescent immunization, may play a role in controlling invasive meningococcal disease.

Coinfections and iterative detection of respiratory viruses among 17,689 patients between March 2021 and December 2022 in Southern France

ObjectivesWe aimed to describe coinfections and iterative infections with respiratory viruses diagnosed over a 22-month period in 2021–2022 in public university hospitals of the second largest French city. Material and methodsRespiratory virus infections were diagnosed by qPCR with the Fast Track Diagnostics Respiratory Pathogens 21 on nasopharyngeal swabs collected between 01/03/2021–31/10/2022 and sent for routine diagnosis purpose to our clinical microbiology-virology laboratory at public university hospitals of Marseille, Southern France. ResultsNasopharyngeal swabs from 17,689 patients were tested, of which 8,133 (46 %) were positive for ≥1 respiratory virus and 1,255 (15%) were co-infected with ≥2 viruses including 213 (2.6 %) with 3–7 viruses. Among them, 1,005 (80 %) were younger than 5 years, and mean age was significantly lower for coinfected than monoinfected patients (6.6 versus 23.8 years; p < 0.0001). Viruses with the highest confection rates were HBoV (97 %), HPeV (97 %), EV (92 %), ADV (68 %), and HCoV-HKU1 (63 %). Iterative infections were observed in 96 patients and they involved 10 different viruses. ConclusionsOur study points out that coinfections with respiratory viruses vary over time in prevalence, involve majoritarily young children, and may involve concurrent acute infections or acute-on-chronic infections, which deserves further specific studies.

Setting thresholds to determine COVID-19 activity levels using the mean standard deviation (MSD) method, England, 2022-2024.

We developed a new activity level setting threshold method, the mean standard deviation (MSD) method to quantify COVID-19 activity levels. This has been validated against the moving epidemic method (MEM), which has been used for influenza for many years, and we observed very similar results. The MSD method can prove to be a tool to use for respiratory viruses with limited historical data or seasonality to quantify activity levels when other respiratory viruses are also circulating.

Effects of immunoproteasome inhibition on acute respiratory infection with murine hepatitis virus strain 1.

Inflammatory responses triggered by acute infection by respiratory viruses such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) drive morbidity and mortality. Infection of mice with murine hepatitis virus strain 1 (MHV-1), a mouse coronavirus, is a useful model to study the pathogenesis of coronavirus respiratory infections. The immunoproteasome is an inducible component of the ubiquitin proteasome system that is poised to contribute to multiple aspects of immune function, inflammation, and protein homeostasis during an infection. We used the MHV-1 model to define the role of the immunoproteasome in coronavirus pathogenesis. We found that immunoproteasome subunit expression increases in the lungs and the liver during acute MHV-1 respiratory infection. Inhibition of immunoproteasome activity did not affect MHV-1 replication but increased MHV-1-induced weight loss, mortality, and inflammation in lungs and livers. Thus, our findings indicate that the immunoproteasome is a critical protective host factor during coronavirus respiratory infection.

Post-disappearance scenarios: policy implications following the potential disappearance of B/Yamagata lineage influenza viruses.

The COVID-19 pandemic and related preventive measures reduced influenza virus circulation, notably causing the disappearance of the B/Yamagata lineage of influenza viruses. In this Perspective, we discuss the implications that this development may have for global influenza epidemiology, and the adjustments that may need to be implemented concerning surveillance strategies and practices, laboratory safety protocols, and influenza vaccine formulations. The disappearance of the B/Yamagata lineage might indeed alter the dynamics of the influenza disease burden (although in a way that is difficult to predict at the moment), and associated diagnostic practices, and may also necessitate updated biosafety levels and revised influenza surveillance strategies. Furthermore, the World Health Organization (WHO) recommended in September 2023 the exclusion of B/Yamagata antigens from future vaccines, with a shift towards trivalent vaccines or modified quadrivalent vaccines; this new scenario underscores the importance of robust global respiratory virus surveillance, effective communication with healthcare professionals and the population to maintain trust in vaccines, and a collaborative approach among health policymakers and vaccine manufacturers to navigate this epidemiological change.

Recombinant characterization and pathogenicity of a novel L1C RFLP-1-4-4 variant of porcine reproductive and respiratory syndrome virus in China

Porcine reproductive and respiratory syndrome (PRRS) is one of the most significant diseases affecting the pig industry worldwide and is caused by the PRRS virus (PRRSV), which has complex genetic variation due to frequent mutations, indels, and recombination. The emergence of PRRSV L1C.5 in 2020 in the United States has raised worldwide concerns about PRRSV with the RFLP 1-4-4 pattern and lineage 1C. However, studies on the pathogenic characteristics, epidemiological distribution, and effectiveness of vaccines against PRRSV with L1C and RFLP1-4-4 pattern in China are still insufficient. In this study, a novel recombinant variant of PRRSV with RFLP 1-4-4 and lineage 1C features, different from L1C.5 in the United States, was isolated in China in 2021. In pathogenicity experiments in specific pathogen-free piglets or farm piglets, 60–100% of artificially infected experimental piglets died with high fever and respiratory symptoms. Inflammatory cytokine and chemokine levels were upregulated in infected piglets. A commercially modified live vaccine against highly pathogenic PRRSV did not provide effective protection when the vaccinated piglets were challenged with the novel L1C-1-4-4 variant. Therefore, this strain merits special attention when devising control and vaccine strategies. These findings suggest that extensive joint surveillance is urgently needed and that vaccine strategies should be updated to prevent the disease from spreading further.

Management of genomic surveillance for respiratory viral infections circulating in the territory of the city of Moscow

Introduction. Outbreaks of respiratory viral infections have an economic impact on the healthcare system and pose a threat to public well-being. Monitoring for the incidence of acute respiratory viral infections in a metropolitan area, especially during the COVID-19 pandemic, was in dire need of an adequate tool to identify mutations and variants that evade vaccine immunity and initiate an increase in incidence. Genomic surveillance was required for a timely response. Purpose of the study. Management of the Moscow Genomic Center for genomic surveillance for acute respiratory viral infections and COVID-19, with an assessment of the results during seasonal outbreaks in the capital. Materials and methods. With the support of the Moscow City Health Department, management and logistics measures were developed and implemented, the NGS testing program in patient samples on a planned basis and during the period of increased incidence of acute respiratory viral infections and COVID-19, technical procedures for high-throughput sequencing were developed, the security of data exchange and biosafety of medical personnel were ensured. Results. The Moscow Genome Center was established within the structure of the Moscow City Health Department. For the period from October 2023 to April 2024, targeted NGS data (a panel of thirty two pathogens, 6528 samples were tested): SARS-COV-2 dominated the entire period, the incidence of influenza A (H3N2) increased sharply from the beginning of December and decreased sharply by the end of January. Sars-CoV-2 genetic lineage rotation: XBB lineage dominated (most represented: XBB.1.16, XBB.1.16.11) from October to the end of January, then JN lineage prevailed (most represented: JN.1, also found: JN.1.13, JN.1.18, JN.1.19, JN.1.4). Influenza A strain rotation: H3N2 (A/Massachusetts/01/2020) and H3N2 (A/Massachusetts/38/2019) dominated from December to February. Research limitations. A targeted panel of 32 respiratory viruses most common in the Moscow population was used for NGS. Incomplete coverage of the entire viriome is a conditional limitation. Conclusion. Representative, high-quality and continuous genetic surveillance has been managed in the capital. The Moscow Genome Center has successfully implemented the NGS Testing Program and support for the Russian Genomic Resource of Microorganisms VGARus.

Adapting COVID-19 research infrastructure to capture influenza and respiratory syncytial virus alongside SARS-CoV-2 in UK healthcare workers winter 2022/23 and beyond: protocol for a pragmatic sub-study

Introduction During the COVID-19 pandemic, extensive research was conducted on SARS-CoV-2; however, important questions about other respiratory pathogens remain unanswered. A severe influenza season in 2022–2023 with simultaneous circulation of SARS-CoV2 and respiratory syncytial virus is anticipated. This sub-study aims to determine the incidence and impact of these respiratory viruses on healthcare workers, the symptoms they experienced, the effectiveness of both COVID-19 and influenza vaccination and the burden of these infections on the National Health Service (NHS) workforce. Methods and analysis This is a longitudinal prospective cohort sub-study, utilising the population and infrastructure of the SARS-CoV-2 Immunity &amp; Reinfection Evaluation (SIREN) study, which focuses on hospital staff in the UK. Participants undergo fortnightly nucleic acid amplification testing on a multiplex assay including SARS-CoV-2, influenza A and B and RSV, regardless of symptoms. Questionnaires are completed every two weeks, capturing symptoms, sick days, exposures, and vaccination records. Serum samples are collected monthly or quarterly from participants associated with a SIREN site. This sub-study commenced on 28/11/22 to align with the predicted influenza season and participants’ influenza vaccine status. The SIREN Participant Involvement Panel shaped the aims and methods for the study, highlighting its acceptability. UK devolved administrations were supported to develop local protocols. Analysis plans include incidence of asymptomatic and symptomatic infection, comparisons of vaccination coverage, assessment of sick day burden, and effectiveness of seasonal influenza against infection and time off work. Data are also integrated into UKHSA nosocomial modelling. Ethics and dissemination The protocol was approved by the Berkshire Research Ethics Committee (IRAS ID 284460, REC Reference 20SC0230) on 14/11/2022. Participants were informed in advance. As the frequency and method of sampling remained the same, implied consent processes were approved by the committee. Participants returning to the study give informed consent. Regular reports to advisory groups and peer-reviewed publications are planned to disseminate findings and inform decision making. Clinical trial registration number: ISRCTN11041050; registration date: 12 January 2021. Sub study included in protocol version: v8.0, and amended in v9.0

System and transcript dynamics of cells infected with severe acute respiratory syndrome virus 2 (SARS-CoV-2)

Statistical laws arise in many complex systems and can be explored to gain insights into their structure and behavior. Here, we investigate the dynamics of cells infected with severe acute respiratory syndrome virus 2 (SARS-CoV-2) at the system and individual gene levels; and demonstrate that the statistical frameworks used here are robust in spite of the technical noise associated with single-cell RNA sequencing (scRNA-seq) data. A biphasic fit to Taylor’s power law was observed, and it is likely associated with the larger sampling noise inherent to the measure of less expressed genes. The type of the distribution of the system, as assessed by Taylor’s parameters, varies along the course of infection in a cell type-dependent manner, but also sampling noise had a significant influence on Taylor’s parameters. At the individual gene level, we found that genes that displayed signals of punctual rank stability and/or long-range dependence behavior, as measured by Hurst exponents, were associated with translation, cellular respiration, apoptosis, protein-folding, virus processes, and immune response. Those genes were analyzed in the context of a protein-protein interaction network to find possible therapeutic targets.

Dayuan Yin alleviates symptoms of HCoV-229E-induced pneumonia and modulates the Ras/Raf1/MEK/ERK pathway

Viral pneumonia is characterized by inflammation in the lungs triggered by respiratory viruses. Dayuan Yin (DYY), a traditional Chinese medicine formula known for treating infectious diseases, is hypothesized to offer therapeutic benefits in treating viral pneumonia, although its specific molecular impacts remain understudied. This study aimed to evaluate the therapeutic effects of DYY in mitigating HCoV-229E virus-induced pneumonia in mice. This study employed an HCoV-229E virus-infected mouse model to investigate the therapeutic potential and underlying molecular mechanisms of DYY on virus-induced pneumonia. The respiratory function and organ indices post-treatment were assessed. Lung tissue and tracheal lesions were evaluated via immunohistochemistry. Spleen immune cell composition was analyzed using flow cytometry. Inflammatory cytokines and viral loads were quantified using hypersensitive multiplex electrochemiluminescence method and PCR analysis, respectively. The expression levels of MAS1, Ras, Raf1, MEK1/2, and ERK1/2 in lung tissues were determined through western blot analysis. DYY significantly improved respiratory function, and reduced organ pathology in infected mice. It effectively decreased viral loads and inflammatory cytokines such as IL-6, IL-1β, and TNF-α in lung tissues. Enhancements in immune response were evidenced by increased CD4/CD8 ratios in the spleen. DYY also notably upregulated MAS1 protein levels and suppressed the activation of the Ras/Raf1/MEK/ERK signaling pathway. DYY enhanced respiratory function and exerted significant antiviral and immunomodulatory effects in mice infected with the HCoV-229E virus, primarily by modulating MAS1 expression and inhibiting the Ras/Raf1/MEK/ERK pathway.Graphical

Seasonality of common respiratory viruses: Analysis of nationwide time-series data.

Understanding the seasonal behaviours of respiratory viruses is crucial for preventing infections. We evaluated the seasonality of respiratory viruses using time-series analyses. This study analysed prospectively collected nationwide surveillance data on eight respiratory viruses, gathered from the Korean Influenza and Respiratory Surveillance System. The data were collected on a weekly basis by 52 nationwide primary healthcare institutions between 2015 and 2019. We performed Spearman correlation analyses, similarity analyses via dynamic time warping (DTW) and seasonality analyses using seasonal autoregressive integrated moving average (SARIMA). The prevalence of rhinovirus (RV, 23.6%-31.4%), adenovirus (AdV, 9.2%-16.6%), human coronavirus (HCoV, 3.0%-6.6%), respiratory syncytial virus (RSV, 11.7%-20.1%), influenza virus (IFV, 11.7%-21.5%), parainfluenza virus (PIV, 9.2%-12.6%), human metapneumovirus (HMPV, 5.6%-6.9%) and human bocavirus (HBoV, 5.0%-6.4%) were derived. Most of them exhibited a high positive correlation in Spearman analyses. In DTW analyses, all virus data from 2015 to 2019, except AdV, exhibited good alignments. In SARIMA, AdV and RV did not show seasonality. Other viruses showed 12-month seasonality. We describe the viruses as winter viruses (HCoV, RSV and IFV), spring/summer viruses (PIV, HBoV), a spring virus (HMPV) and all-year viruses with peak incidences during school periods (RV and AdV). This is the first study to comprehensively analyse the seasonal behaviours of the eight most common respiratory viruses using nationwide, prospectively collected, sentinel surveillance data.

Diagnostic utility of rapid antigen testing as point-of-care test for influenza and other respiratory viruses in patients with acute respiratory illness

This study investigates the prevalence and clinical characteristics of respiratory viruses among patients with acute respiratory illness (ARI) in a low-resource setting, using a rapid antigen test as a point-of-care test (POCT). We included 343 patients presenting with ARI symptoms at an outpatient pulmonary clinic from December 2023 to April 2024. Nasopharyngeal swabs were tested for SARS-CoV-2, influenza A/B, respiratory syncytial virus, and adenovirus using POCT. The overall prevalence of respiratory viruses was 21.2%, with influenza A being the most common (11.4%). Shorter duration of symptoms and lower lymphocyte counts were associated with higher influenza positivity. Patients who tested positive for influenza received significantly more antiviral therapy (98.1% vs. 39.4%, p<0.001) and less antibiotic therapy (1.9% vs. 28.5%, p<0.001) compared to those who tested negative. The study highlights the utility of rapid antigen testing in enhancing antiviral and antibiotic stewardship, thereby improving clinical decision-making and patient outcomes in resource-limited settings.

An Outbreak of Respiratory Viral Infections in a Professional Ice Hockey Team.

Viral acute respiratory infections (ARIs) are an important cause of illness in athletes. However, their impact on ice hockey players is unclear. We describe an outbreak of ARIs in a professional ice hockey team. Contrary to expected influenza, the 40-day outbreak was caused by 8 different respiratory viruses, that is, 2 different influenza A viruses, human coronavirus-NL63 (HCoV-NL63), respiratory syncytial viruses (RSV) A and B, 2 different rhinoviruses, enterovirus D68, and parainfluenza type 2 virus. Only influenza A and HCoV-NL63 were possibly spread within the team thus suggesting an important contraction from the community. The burden of illness was substantial.

Identification of new antigenic epitopes of porcine reproductive and respiratory syndrome virus nsp12 protein using monoclonal antibodies

Porcine reproductive and respiratory syndrome virus (PRRSV), a member of the arteritis virus family, significantly impacts the swine industry due to its high infectiousness. nsp12, the nonstructural protein encoded by PRRSV, is a membrane-associated protein, with limited knowledge about its antigenic properties and functions. In this study, we used the expressed and purified nsp12 protein as antigen to immunize mice, and successfully screened five positive hybridoma cell lines that stably secrete anti-nsp12 monoclonal antibodies using immunological assays such as indirect ELISA and IFA. The antigenic epitopes recognized by the five monoclonal antibodies were identified using the fusion expression of peptides derived from the overlapping truncators of the nsp12 gene. The results showed that monoclonal antibodies 3G11 and 9C2 recognized the antigenic epitope 93TWGFESDTAY102, 2E3 recognized 115DYNDAFRARQ124, and 10G6 and 2A4 recognized 142PGPVIEPTL150. Furthermore, the three newly identified antigenic epitopes were all immunodominant and located on the surface of nsp12 protein. Notably, the antigenic epitopes 93–102 aa are all highly conserved across PRRSV-2 strains, making them suitable targets for PRRSV-2 detection. In conclusion, our findings advance the understanding of the antigenic properties of the PRRSV nsp12 protein and facilitate the development of assays for PRRSV detection.

Clinical Characteristics and Outcomes of Hospitalized AECOPDs Secondary to SARS-CoV-2 versus Other Respiratory Viruses

Clinical Characteristics and Outcomes of Hospitalized AECOPDs Secondary to SARS-CoV-2 versus Other Respiratory Viruses

An Overview of Pediatric Pulmonary Complications During COVID-19 Pandemic: A Lesson for Future.

The pediatric community is considered a suitable target for controlling the spread and mortality of viral diseases. In late December 2019, a respiratory disease due to the novel coronavirus, later COVID-19, hit the globe. The COVID-19 global disruption had direct and indirect impacts on different aspects of child health. Therefore, surveillance, preventive approaches, and treatment plans for children came into the spotlight. This study aims to discuss the clinical pictures as well as laboratory and radiological findings of the infected children during the COVID-19 pandemic. The focus of this study is to express the clinical manifestations of respiratory disease in pediatric SARS-CoV-2, available therapeutic options, vaccine recommendations, and long COVID sequelae in affected children. This review could serve as a hint for upcoming challenges in pediatric care during future pandemics. The clinical presentation of COVID-19 in pediatrics can range from mild pulmonary disease to acute respiratory distress syndrome (ARDS). Supportive care is a crucial component of the management of pediatric COVID-19. However, the importance of specializing in how to treat patients with more severe conditions cannot be overstated. Additionally, clinicians must consider prevention strategies as well as potential complications. Although the infected patients are dipping day by day, there is a lack of clinical guidelines for pediatric SARS-CoV-2-associated pulmonary diseases. Understanding of the physicians about all aspects of pediatric care during the COVID-19 pandemic could lead to enhanced quality of future patient care and safety, reduced costs of health policies, and surveil the risk that patients with respiratory viruses can expose to society.

T Lymphocyte Mitochondrial Markers as Independent Risk Factors for Poor Prognosis of COVID-19.

Severe Acute Respiratory Syndrome Virus 2 (SARS-CoV-2) primarily targets mitochondria. However, the description of mitochondrial signaling in immune cells remains limited in COVID-19. This study aimed to elucidate the pivotal roles played by immune cells and mitochondria in the pathogenesis of COVID-19 and the resulting clinical outcomes. We obtained epidemiological characteristics, laboratory parameters and T cell mitochondrial damage indicators in 296 COVID-19 patients. And we further evaluated the predictive value of novel T lymphocyte mitochondrial markers and conventional immune inflammatory markers as clinical outcomes in COVID-19 patients. Finally, Binary logistic regression analysis was conducted to identify the independent risk factors associated with the prognosis of patients with COVID-19. The severe group exhibited lower counts of Mito+CD3+, Mito+CD4+, and Mito+CD8+ cells compared to the non-severe group. Significantly higher positive rates of CD3+, CD3+CD4+, and CD3+CD8+T cell mitochondrial damage were observed in the severe group compared to the non-severe group. The CD3+CD8+T cells MMP-low% had the highest AUC value of 0.864 (95% CI =0.794-0.934) to evaluate COVID-19 outcome. Binary logistic regression analysis showed that CD3+T cells MMP-low%, CD3+CD4+T cells MMP-low% and CD3+CD8+T cells MMP-low% were independent risk factors for adverse outcomes in COVID-19 patients. Our research suggests that a substantial proportion of COVID-19 patients exhibited mitochondrial impairment with T-lymphocyte. T cells mitochondrial markers can serve as predictive factors and independent risk factors for predicting adverse outcomes in COVID-19 patients.

The effects of ventilation layout on cough droplet dynamics relating to seasonal influenza

The primary aim of this paper is to investigate airborne virus transmission in a typical meeting room relating to the heating, ventilation, and air conditioning (A.C.) systems. While the installation of 4-way cassette A.C. systems in offices and meeting rooms has become increasingly common, their efficiency in mitigating short-range airborne virus spread remains poorly understood. Addressing this gap is critical in the post-pandemic era, where understanding the limitations of various ventilation systems is paramount for public health. We systematically compare the performance of the 4-way cassette A.C., various configurations of mixing and displacement ventilation systems, and natural ventilation in controlling the spread of respiratory viruses. Our research uniquely integrates evaporation models to accurately simulate cough clouds' multiphase behavior under both quiescent and thermally influenced conditions. The study benchmarks these systems against two widely recognized ventilation standards (i.e., 5 air changes per hour and 10 l/s per person), offering evidence-based insights applicable across diverse indoor settings. Our findings reveal significant thermal effects in the quiescent case, resulting in 32.3%, 54.3%, and 8.0% changes in the axial, vertical, and lateral spread of the virus-laden droplets, respectively. Notably, the 0.5 m/s 4-way cassette A.C. system demonstrated superior performance, reducing the axial spread by 29.6% compared to other mechanical ventilation configurations. Furthermore, the role of exhaust outlets or doors was found to be critical in shaping the spread pattern in natural ventilation scenarios. This work can offer practical guidance to office workers, engineers, and public health officials on enhancing indoor airborne infection control.

Factors Associated With Transmission Across Three Waves of SARS-CoV-2 in a Prospective Community-Based Study of Households With School-Aged Children-Dane County, Wisconsin, 2020-2022.

Household transmission of SARS-CoV-2 is a driver of the ongoing COVID-19 pandemic. Understanding factors that contribute to secondary infection risks (SIRs) can define changing trends and inform public health policies. The ORegon CHild Absenteeism due to Respiratory Disease Study (ORCHARDS) prospectively monitors respiratory viruses within the Oregon School District (OSD) in southcentral Wisconsin. Households with students who had ≥ 2 respiratory symptoms were eligible and opted to participate in ORCHARDS. Between October 28, 2020, and May 16, 2022, all household members provided self-collected nasal specimens on days 0, 7, and 14 for SARS-CoV-2 detection using real-time reverse-transcription-polymerase chain reaction. We used logistic regression to investigate individual- and household-level characteristics associated with SARS-CoV-2 transmission. Overall, 127 households comprising 572 individuals (48% female; 52% male; 0.4% nonbinary; 77% ≥ 18 years) had at least one detection of SARS-CoV-2. The overall SIR was 47% and decreased over time (pre-Delta = 72% [95% CI: 58%-83%]; Delta = 51% [40%-63%]; and Omicron = 41% [36%-47%]). Odds of household transmission were 63% lower during the Omicron period compared with the pre-Delta period (OR = 0.36 [95% CI: 0.13-0.94] p = 0.037). Greater household density (members/bedroom) was significantly associated with household transmission during the Omicron period (OR = 6.8, [2.19-21.37] p = 0.001). Index case age, illness severity, and individual symptoms were not significantly associated with odds of household transmission. Greater household density was associated with a higher risk of SARS-CoV-2 transmission, but the risk declined over time with subsequent variants. Interplay between variants, prior infection, and individual/household factors may identify modifiable factors (e.g., behavior and vaccination) to reduce future transmission risk.