BACKGROUND: Serology for dengue viruses (DENV) and Zika virus (ZIKV) has been hindered by antibody cross-reactivity, which limits the utility of these tests for surveillance and assessment of sero-status. Our aim was to develop a multiplexed IgG-based assay with increased accuracy to assess the history of previous DENV and ZIKV infections. METHODS: We developed and assessed the analytical performance of a sample-sparing, multiplexed, microsphere-based serological assay using domain III of the envelope protein (EDIII) of DENV serotypes 1-4 and ZIKV, the most variable region between each virus. We used a reference panel of well-characterised serum samples from US-based travellers or residents of southeast Asia, central America, or Puerto Rico, who were naive or immune to either or both DENV and ZIKV, to develop an algorithm for detecting previous exposure to DENV and ZIKV and identify optimal positivity cutoffs to maximise assay performance. To independently confirm the performance of the assay and algorithm, we used a second test set of previously collected samples from healthy children (aged 9-16 years) living in Puerto Rico, whose DENV and ZIKV serostatus had been defined using the gold-standard virus neutralisation assay. We evaluated the performance of the multiplex assay compared with the gold-standard assay by estimating sensitivity and specificity for identification of past exposure to ZIKV and DENV. FINDINGS: The multiplexed EDIII assay showed reproducible results over different days and a linearity range from μg to pg levels for various EDIII antigens. Using a reference panel of serum samples from individuals who were DENV naive (n=136), DENV immune (n=38), ZIKV naive (n=67), and ZIKV immune (n=28), we optimised the assay and developed a testing algorithm that was 94·9% (95% CI 83·1-99·1) sensitive and 97·1% (92·7-98·9) specific for identifying previous exposure to DENV, and 100% (95% CI 88·0-100) sensitive and 97·0% (89·8-99·5) specific for identifying previous exposure to ZIKV. In an analysis with an independent test set of 389 samples, the assay and algorithm had 94·2% (89·9-97·1) sensitivity and 92·9% (87·3-96·5) specificity for DENV, and 94·1% (88·7-97·4) sensitivity and 95·0% (90·0-98·0) specificity for ZIKV. INTERPRETATION: The multiplexed EDIII serology assay can accurately identify the history of previous infection with either DENV or ZIKV. This high-throughput and sample-sparing assay is a promising new tool for supporting flavivirus surveillance, epidemiological and clinical studies, and serological testing for dengue vaccine eligibility. Further studies are needed to reduce the cost of the assay, eliminate high background in some samples, and to assess performance in DENV-endemic and ZIKV-endemic countries. FUNDING: US National Institutes of Health.

Nursing home residents are at elevated risk for severe complications from respiratory viruses, including SARS-CoV-2, influenza, and respiratory syncytial virus (RSV). Nursing homes are required to report COVID-19 vaccination coverage and can voluntarily report influenza and RSV vaccination coverage among residents to CDC's National Healthcare Safety Network. The purpose of this study was to assess COVID-19, influenza, and RSV vaccination coverage among nursing home residents early in the 2024-25 respiratory virus season. As of November 10, 2024, 29.7% of nursing home residents had received a 2024-2025 COVID-19 vaccine. Among residents at facilities that elected to report vaccination against influenza (59.4% of facilities) and RSV (51.8% of facilities), 58.4% had received influenza vaccination, and 17.9% had received RSV vaccination. Vaccination coverage varied by U.S. Department of Health and Human Services region, social vulnerability index level, and facility size. Addressing low coverage with COVID-19, influenza, and RSV vaccines is a priority to protect residents who are susceptible to severe outcomes associated with respiratory illnesses.

OBJECTIVE: To examine temporal changes in coverage with a complete primary series of coronavirus disease 2019 (COVID-19) vaccination and staffing shortages among healthcare personnel (HCP) working in nursing homes in the United States before, during, and after the implementation of jurisdiction-based COVID-19 vaccination mandates for HCP. SAMPLE AND SETTING: HCP in nursing homes from 15 US jurisdictions. DESIGN: We analyzed weekly COVID-19 vaccination data reported to the Centers for Disease Control and Prevention's National Healthcare Safety Network from June 7, 2021, through January 2, 2022. We assessed 3 periods (preintervention, intervention, and postintervention) based on the announcement of vaccination mandates for HCP in 15 jurisdictions. We used interrupted time-series models to estimate the weekly percentage change in vaccination with complete primary series and the odds of reporting a staffing shortage for each period. RESULTS: Complete primary series vaccination among HCP increased from 66.7% at baseline to 94.3% at the end of the study period and increased at the fastest rate during the intervention period for 12 of 15 jurisdictions. The odds of reporting a staffing shortage were lowest after the intervention. CONCLUSIONS: These findings demonstrate that COVID-19 vaccination mandates may be an effective strategy for improving HCP vaccination coverage in nursing homes without exacerbating staffing shortages. These data suggest that mandates can be considered to improve COVID-19 coverage among HCP in nursing homes to protect both HCP and vulnerable nursing home residents.

OBJECTIVE: Epidemiologic data for mixed connective tissue disease (MCTD) are limited. Leveraging data from the Manhattan Lupus Surveillance Program (MLSP), a racially/ethnically diverse population-based registry of cases with SLE and related diseases including MCTD, we provide estimates of the prevalence and incidence of MCTD. METHODS: MLSP cases were identified from rheumatologists, hospitals, and population databases using a variety of ICD-9 codes. MCTD was defined as one of the following: 1) fulfillment of our modified Alarcon-Segovia and Kahn criteria which required a positive RNP antibody and the presence of synovitis, myositis, and Raynaud's phenomenon, 2) a diagnosis of MCTD and no other diagnosis of another connective tissue disease (CTD), and 3) a diagnosis of MCTD regardless of another CTD diagnosis. RESULTS: Overall, 258 (7.7%) of cases met a definition of MCTD. Using our modified Alarcon-Segovia and Kahn criteria for MCTD, the age-adjusted prevalence was 1.28 (95%CI 0.72-2.09) per 100 000. Using our definition of a diagnosis of MCTD and no other diagnosis of another CTD yielded an age-adjusted prevalence and incidence of MCTD of 2.98 (95%CI 2.10-4.11) per 100 000 and 0.39 (95%CI 0.22-0.64) per 100 000, respectively. The age-adjusted prevalence and incidence were highest using a diagnosis of MCTD regardless of other CTD diagnoses and were 16.22 (95%CI 14.00-18.43) per 100 000 and 1.90 (95%CI 1.49-2.39) per 100 000 respectively. CONCLUSIONS: The MLSP provided estimates for prevalence and incidence of MCTD in a diverse population. The variation in estimates using different case definitions is reflective of the challenge of defining MCTD in epidemiologic studies.

OBJECTIVE: The objective of this surveillance project was to determine the prevalence of mixed connective tissue disease (MCTD) in 2007 in the Indian Health Service (IHS) active clinical population from 3 regions of the United States. METHODS: The IHS Lupus Registry was designed to identify possible MCTD cases in addition to lupus. The population denominator for this report includes American Indian or Alaska Native adults within the IHS active clinical population in 2007, residing in select communities in 3 regions of the US. Potential MCTD cases were identified using a broad range of diagnostic codes and were confirmed by detailed medical record abstraction. Classification as MCTD for this analysis required both rheumatologist diagnosis of MCTD without diagnosis of other connective tissue disease and documentation of the Alarcon-Segovia criteria in the medical record. Prevalence was also calculated using two alternate definitions of MCTD. RESULTS: The age-adjusted prevalence of MCTD using our primary definition was 6.4 per 100,000 (95% confidence interval (CI) 2.8-12.8). The prevalence was higher in women than men using all three definitions of MCTD, and no men met the primary definition of MCTD. CONCLUSION: The first population-based estimates of the prevalence of MCTD in the US American Indian/Alaska Native population show that the prevalence appears to be higher than in other populations. Additional population-based estimates are needed to better understand the epidemiology of MCTD.