Hidden heterogeneity and its influence on dengue vaccination impact

Previous Dengue Infection among Children in Puerto Rico and Implications for Dengue Vaccine Implementation

Limited dengue virus (DENV) seroprevalence estimates are available for Puerto Rico, which are needed to inform the potential use and cost-effectiveness of DENV vaccines. The Communities Organized to Prevent Arboviruses (COPA) is a cohort study initiated in 2018 in Ponce, Puerto Rico, to assess arboviral disease risk and provide a platform to evaluate interventions. We recruited participants from households in 38 study clusters, who were interviewed and provided a serum specimen. Specimens from 713 children aged 1 to 16 years during the first year of COPA were tested for the four DENV serotypes and ZIKV using a focus reduction neutralization assay. We assessed the seroprevalence of DENV and ZIKV by age and developed a catalytic model from seroprevalence and dengue surveillance data to estimate the force of infection for DENV during 2003-2018. Overall, 37% (n = 267) were seropositive for DENV; seroprevalence was 9% (11/128) among children aged 1 to 8 years and 44% (256/585) among children aged 9 to 16 years, exceeding the threshold over which DENV vaccination is deemed cost-effective. A total of 33% were seropositive for ZIKV, including 15% among children aged 0 to 8 years and 37% among children aged 9 to 16 years. The highest force of infection occurred in 2007, 2010, and 2012-2013, with low levels of transmission from 2016 to 2018. A higher proportion of children had evidence of multitypic DENV infection than expected, suggesting high heterogeneity in DENV risk in this setting.

Fitting logistic regression models to assess vitamin D deficiency with clinical parameters in chronic hepatitis B patients

Statistical models provide a quantitative structure with which clinicians can evaluate their hypotheses to explain patterns in observed data and generate forecasts. In contrast, vitamin D is an important immune modulator that plays an emerging role in liver diseases such as chronic hepatitis B (CHB). Therefore, we quantified 25(OH)D₃ serum levels in 292 CHB patients tested for their association with clinical parameters. Of 292 patients, 69 (63%), 95 (47%), and 39 (19%) had severe vitamin D deficiency (25(OH)D₃ < 10 ng/mL), vitamin D insufficiency (25(OH)D₃10 and < 20 ng/mL), or adequate vitamin D serum levels (25(OH)D₃ 20 ng/mL), respectively. In both univariate and multivariate analyses, zinc serum level was a strong predictor of low 25(OH)D₃ serum levels (P < 0.001). Results of fitted models showed that lower vitamin D levels were significantly associated with: younger age, lower uric acid levels, HBeAg-positive status, lower calcium levels (p < 0.05). Vitamin D deficiency (<20 ng/ml) or severe deficiency (<10 ng/ml) was observed more frequently among HBV patients (52%). Vitamin D deficiency was observed in most CHB patients. Generally, our results recommend that substitution of vitamin D can be a substitution method in the treatment of patients with HBV-associated disorders.