Influenza and Other Respiratory Viruses

BackgroundSeasonal influenza exhibits distinct spatiotemporal patterns across the United States, yet the geographic clustering of influenza activity remains incompletely understood. This study aims to identify jurisdictions with similar patterns of seasonal influenza epidemics by exploring spatiotemporal dynamics across the United States after the 2009 H1N1 pandemic. MethodsWe analyzed data from U.S. influenza surveillance systems, including outpatient illness surveillance and virologic surveil...

Understanding the dynamics of antibody responses following vaccination and SARS-CoV-2 infection is important for informing effective vaccination strategies and other public health interventions. This study investigates SARS-CoV-2 antibody dynamics in a Puerto Rican cohort, analyzing how IgG levels vary by vaccination status and previous infection. We assess waning immunity and the distribution of hybrid immunity with the aim to inform public health strategies and vaccination programs in Puerto R...

BackgroundWe previously reported that nasal SARS-CoV-2 viral loads (VL) peaked around the fourth day of symptoms in highly immune adults sampled April 2022 - April 2023, while influenza A VL peaked soon after symptom onset. We hypothesized that SARS-CoV-2 kinetics may have changed due to reduced COVID-19 incidence and altered vaccination patterns. Understanding how viral kinetics evolve over time is essential to inform testing strategies. MethodsParticipants with symptomatic upper respiratory i...

Background & AimsSeasonal respiratory viruses such as influenza cause substantial illness in the United States, over-whelming healthcare facilities and reducing economic productivity. Effective surveillance of these viruses is therefore critical for timely risk communication, strategic resource allocation, and coor-dinated public health responses that mitigate viral spread. Syndromic surveillance, which tracks patient symptoms rather than confirmed diagnostic results, plays an essential role in ...

BackgroundInfluenza and respiratory syncytial virus (RSV) are major contributors to the burden of seasonal influenza-like illnesses (ILI) in the US. The prevention and treatment of ILI varies substantially across age groups and in cost and administration schedule. Clearly identifying the times when healthcare resources are most needed to mitigate the effects of seasonal RSV and influenza outbreaks will improve public health responses before and during ILI seasons. MethodsWe implemented stacked-...

IntroductionFew studies have examined the incidence of virologic-confirmed influenza virus and respiratory syncytial virus (RSV) infections in community-dwelling older adults. MethodsWe enrolled adults aged 60-89 years in Jiangsu Province, China and followed them weekly from December 2015-September 2017 to identify acute respiratory illnesses (ARI), collect illness information and respiratory specimens for laboratory testing. Results1,527 adults were enrolled, 0{middle dot}4% reported ever rec...

Understanding the spatiotemporal dynamics of seasonal influenza spread across the United States (US) is crucial for informed public health planning. We explored patterns of influenza transmission during the 2022/23 season in the US and used a mathematical model to infer potential drivers and underlying mechanisms. Leveraging emergency department visit data, we first estimated the timing of influenza onset for the 2022/23 season at the Health Service Area (HSA) level. We then combined the estimat...

Seasonal influenza causes substantial morbidity and mortality in the United States. The U.S. Centers for Disease Control and Prevention (CDC) uses a compartmental framework to estimate the annual disease burden and burden prevented by vaccination for all influenza types and subtypes combined. However, these estimates do not capture underlying shifts in disease burden caused by different circulating influenza virus types or subtypes. We demonstrate an extension of the current framework to estimat...

BackgroundThe comparative risk of post-acute sequelae (PAS) associated with SARS-CoV-2 and influenza virus infection remains unclear. MethodsWe undertook a retrospective cohort study within the Kaiser Permanente Southern California healthcare system of COVID-19 and influenza cases who received acute respiratory illness (ARI) diagnoses in virtual, outpatient, or inpatient settings between 1 September, 2022 and 31 December, 2023. We monitored PAS-associated healthcare utilization across all setti...

ObjectivesTo evaluate reinfection rates and protective effectiveness of prior disease among patients with coronavirus disease 2019 (COVID-19) infection in the United States. DesignRetrospective cohort study SettingOne multi-hospital health system in Ohio and Florida ParticipantsAll 150,325 patients who were tested for COVID-19 infection via PCR from March 12, 2020 to August 30, 2020. Testing performed up to January 7, 2021 in these patients was included for analysis. Healthcare workers were e...

BackgroundSymptoms of COVID-19 including fatigue and dyspnea, may persist for weeks to months after SARS-CoV-2 infection. This study compared self-reported disability among SARS-CoV-2-positive and negative persons with mild to moderate COVID-19-like illness who presented for outpatient care before widespread COVID-19 vaccination. MethodsUnvaccinated adults with COVID-19-like illness enrolled within 10 days of illness onset at three US Flu Vaccine Effectiveness Network sites were tested for SARS...

On September 1, 2022, Moderna and Pfizer-BioNTech bivalent vaccines replaced existing monovalent vaccines as booster doses against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) for persons aged 12 and older in the United States. We assessed the effectiveness of these bivalent boosters against Omicron infection and severe outcomes (COVID-19 hospitalization and death) over a 9.5-month period using line-level data from the state of Nebraska. We found that the relative effectiveness o...

Mathematical and computational models are often used to forecast respiratory infectious disease burden, including to inform healthcare capacity requirements. We aimed to characterize pathways of clinical progression associated with SARS-CoV-2, influenza, and respiratory syncytial virus (RSV) infections using data from patients in an integrated healthcare system, whose encounters were monitored across all levels of acuity spanning virtual, ambulatory, and inpatient care settings. Using parametric...

BackgroundCoronavirus disease 2019 (COVID-19) vaccines have been shown to be highly effective in preventing SARS-CoV-2 infection within controlled trials and real-world vaccine effectiveness (VE) studies. Recent reports have estimated reduced VE with the emergence and dissemination of the B.1.617.2 variant ("Delta variant"). We assess VE in Multnomah County, Oregon during a delta variant related epidemic expansion. MethodsA test-negative design (TND) matched case-control analysis was performed ...

BackgroundRSV is a leading cause of ARI, including CAP, in older adults, but available data often substantially underestimate incidence. We estimated RSV-related ARI hospitalization incidence from a prospective CAP study and adjusted for undiagnosed RSV infections due to use of nasopharyngeal/nasal swab testing only. MethodsWe conducted active, population-based surveillance of adult CAP hospitalizations in Thuringia (Germany) between 2021-2023. Participant nasopharyngeal/nasal swabs were RSV-te...

BackgroundThe 2023-24 U.S. influenza season was characterized by a predominance of A(H1N1)pdm09 virus circulation with co-circulation of A(H3N2) and B/Victoria viruses. We estimated vaccine effectiveness (VE) in the United States against mild-to-moderate medically attended influenza illness in the 2023-24 season. MethodsWe enrolled outpatients aged [≥]8 months with acute respiratory illness in 7 states. Respiratory specimens were tested for influenza type/subtype by reverse-transcriptase pol...

BackgroundThe first RSV vaccines for adults 60 years and older were approved prior to the 2023-2024 respiratory virus season. This study used data from adults 60 years and older, enrolled into the Community Vaccine Effectiveness (CoVE) cohort study, in Michigan, U.S.A, to evaluate RSV vaccine effectiveness (VE) and antibody correlates of protection. MethodsA Cox proportional hazards model was used to compare incidence of symptomatic / all RSV infections in those vaccinated versus unvaccinated. ...

BackgroundMultiple prophylactic products are now available to protect against respiratory syncytial virus (RSV) in different age groups. Assessing the pre-intervention burden of RSV infections across various severity levels and risk groups is crucial, as it provides a baseline for evaluating the impact of these products. MethodsWe obtained monthly time series data on hospitalizations, intensive care unit (ICU) admissions, and deaths by age group, ZIP code, and cause for New York state from 2005...

ObjectiveRespiratory syncytial virus (RSV) is a common respiratory pathogen not only in children, but also in adults. Country-specific data on the epidemiology and burden of disease are essential for policy decisions. In view of a recent authorization of adult RSV vaccines, we aimed to comprehensively collect and assess evidence on the epidemiology and burden of RSV in Italian adults. MethodsA systematic literature review was conducted according to the available guidelines. Random-effects propo...

IntroductionWhile seasonal influenza and other respiratory pathogens cause significant morbidity and mortality each year, the community-based burden of these infections remains incompletely understood. Understanding the prevalence, epidemiology, and transmission dynamics of respiratory pathogen infections among community-dwelling individuals is essential during pandemic and epidemic settings and for developing pandemic-preparedness infrastructure. Methods and AnalysisWe present the protocol for...