Background Recent studies suggest a role for vitamin D in innate immunity, including the prevention of respiratory tract infections (RTIs). We hypothesize that serum 25-hydroxyvitamin D (25[OH]D) levels are inversely associated with self-reported recent upper RTI (URTI). Methods We performed a secondary analysis of the Third National Health and Nutrition Examination Survey, a probability survey of the US population conducted between 1988 and 1994. We examined the association between 25(OH)D level and recent URTI in 18 883 participants 12 years and older. The analysis adjusted for demographics and clinical factors (season, body mass index, smoking history, asthma, and chronic obstructive pulmonary disease). Results The median serum 25(OH)D level was 29 ng/mL (to convert to nanomoles per liter, multiply by 2.496) (interquartile range, 21–37 ng/mL), and 19% (95% confidence interval [CI], 18%–20%) of participants reported a recent URTI. Recent URTI was reported by 24% of participants with 25(OH)D levels less than 10 ng/mL, by 20% with levels of 10 to less than 30 ng/mL, and by 17% with levels of 30 ng/mL or more (P<.001). Even after adjusting for demographic and clinical characteristics, lower 25(OH)D levels were independently associated with recent URTI (compared with 25[OH]D levels of ≥30 ng/mL: odds ratio [OR], 1.36; 95% CI, 1.01–1.84 for <10 ng/mL and 1.24; 1.07–1.43 for 10 to <30 ng/mL). The association between 25(OH)D level and URTI seemed to be stronger in individuals with asthma and chronic obstructive pulmonary disease (OR, 5.67 and 2.26, respectively). Conclusions Serum 25(OH)D levels are inversely associated with recent URTI. This association may be stronger in those with respiratory tract diseases. Randomized controlled trials are warranted to explore the effects of vitamin D supplementation on RTI.

OBJECTIVE: To examine temporal trend in the national incidence of bronchiolitis hospitalizations, use of mechanical ventilation, and hospital charges between 2000 and 2009. METHODS: We performed a serial, cross-sectional analysis of a nationally representative sample of children hospitalized with bronchiolitis. The Kids Inpatient Database was used to identify children &lt;2 years of age with bronchiolitis by International Classification of Diseases, Ninth Revision, Clinical Modification code 466.1. Primary outcome measures were incidence of bronchiolitis hospitalizations, mechanical ventilation (noninvasive or invasive) use, and hospital charges. Temporal trends were evaluated accounting for sampling weights. RESULTS: The 4 separated years (2000, 2003, 2006, and 2009) of national discharge data included 544 828 weighted discharges with bronchiolitis. Between 2000 and 2009, the incidence of bronchiolitis hospitalization decreased from 17.9 to 14.9 per 1000 person-years among all US children aged &lt;2 years (17% decrease; Ptrend &lt; .001). By contrast, there was an increase in children with high-risk medical conditions (5.9%–7.9%; 34% increase; Ptrend &lt; .001) and use of mechanical ventilation (1.9%–2.3%; 21% increase; Ptrend = .008). Nationwide hospital charges increased from $1.34 billion to $1.73 billion (30% increase; Ptrend &lt; .001); this increase was driven by a rise in the geometric mean of hospital charges per case from $6380 to $8530 (34% increase; Ptrend &lt; .001). CONCLUSIONS: Between 2000 and 2009, we found a significant decline in bronchiolitis hospitalizations among US children. By contrast, use of mechanical ventilation and hospital charges for bronchiolitis significantly increased over this same period.

OBJECTIVE Single-center studies have suggested that hypovitaminosis D is widespread. Our objective was to determine the serum levels of 25-hydroxyvitamin D (25[OH]D) in a nationally representative sample of US children aged 1 to 11 years. METHODS Data were obtained from the 2001–2006 National Health and Nutrition Examination Survey. Serum 25(OH)D levels were determined by radioimmunoassay and categorized as <25, <50, and <75 nmol/L. National estimates were obtained by using assigned patient visit weights and reported with 95% confidence intervals (CIs). RESULTS During the 2001–2006 time period, the mean serum 25(OH)D level for US children aged 1 to 11 years was 68 nmol/L (95% CI: 66 –70). Children aged 6 to 11 years had lower mean levels of 25(OH)D (66 nmol/L [95% CI: 64 –68]) compared with children aged 1 to 5 years (70 nmol/L [95% CI: 68 –73]). Overall, the prevalence of levels at <25 nmol/L was 1% (95% CI: 0.7–1.4), <50 nmol/L was 18% (95% CI: 16–21), and <75 nmol/L was 69% (95% CI: 65–73). The prevalence of serum 25(OH)D levels of <75 nmol/L was higher among children aged 6 to 11 years (73%) compared with children aged 1 to 5 years (63%); girls (71%) compared with boys (67%); and non-Hispanic black (92%) and Hispanic (80%) children compared with non-Hispanic white children (59%). CONCLUSIONS On the basis of a nationally representative sample of US children aged 1 to 11 years, millions of children may have suboptimal levels of 25(OH)D, especially non-Hispanic black and Hispanic children. More data in children are needed not only to understand better the health implications of specific serum levels of 25(OH)D but also to determine the appropriate vitamin D supplement requirements for children.

Kids' Inpatient Databases) of children (age ,2 years) hospitalized for bronchiolitis. We identified all children hospitalized with bronchiolitis by using International Classification of Diseases, Ninth Revision, Clinical Modification 466.1 and International Classification of Diseases, 10th Revision, Clinical Modification J21. Complex chronic conditions were defined by the pediatric complex chronic conditions classification by using inpatient data. The primary outcomes were the incidence of bronchiolitis hospitalizations, mechanical ventilation use, and hospital direct cost. We examined the trends accounting for sampling weights. RESULTS: From 2000 to 2016, the incidence of bronchiolitis hospitalization decreased from 17.9 to 13.5 per 1000 person-years in US children (25% decrease; P trend , .001). In contrast, the proportion of bronchiolitis hospitalizations among overall hospitalizations increased from 16% to 18% (P trend , .001). There was an increase in the proportion of children with a complex chronic condition (6%-13%; 117% increase), hospitalization to children's hospital (15%-29%; 93% increase), and mechanical ventilation use (2%-5%; 184% increase; all P trend , .

Bronchiolitis admissions cost more than 500 million dollars annually. A codiagnosis of bronchiolitis and pneumonia almost doubles the cost of the hospitalization. Inpatient health care costs of bronchiolitis are higher than estimated previously and highlight the need for initiatives to safely reduce bronchiolitis hospitalizations and thereby decrease health care costs.

Little is known about the relationship between specific composition of the airway microbiota and severity of bronchiolitis. We aimed to identify nasopharyngeal microbiota profiles and to link these profiles to acute severity in infants hospitalized for bronchiolitis. We conducted a multicenter prospective cohort study of 1005 infants (age <1 year) hospitalized for bronchiolitis over three winters, 2011-2014. By applying a 16S rRNA gene sequence and clustering approach to the nasopharyngeal aspirates collected within 24 hours of hospitalization, we determined nasopharyngeal microbiota profiles and their association with bronchiolitis severity. The primary outcome was intensive care use – i.e., admission to an intensive care unit or use of mechanical ventilation. We identified four distinct nasopharyngeal microbiota profiles – three profiles were dominated by either Haemophilus, Moraxella, or Streptococcus, while the fourth profile had the highest bacterial richness. The rate of intensive care use was highest in infants with a Haemophilus-dominant profile and lowest in those with a Moraxella-dominant profile (20.2% vs 12.3%; unadjusted OR, 1.81; 95%CI, 1.07-3.11; P=0.03). After adjusting for 11 patient-level confounders, the rate remained significantly higher in infants with a Haemophilus-dominant profile (OR, 1.98; 95%CI, 1.08-3.62; P=0.03). These findings were externally validated in a separate cohort of 307 children hospitalized for bronchiolitis.

OBJECTIVE We evaluated vitamin D insufficiency in a nationally representative sample of women and assessed the role of vitamin supplementation. STUDY DESIGN We conducted secondary analysis of 928 pregnant and 5173 nonpregnant women aged 13–44 years from the National Health and Nutrition Examination Survey 2001–2006. RESULTS The mean 25-hydroxyvitamin D (25[OH]D) level was 65 nmol/L for pregnant women and 59 nmol/L for nonpregnant women. The prevalence of 25(OH)D <75 nmol/L was 69% and 78%, respectively. Pregnant women in the first trimester had similar 25(OH)D levels as nonpregnant women (55 vs 59 nmol/L), despite a higher proportion taking vitamin D supplementation (61% vs 32%). However, first-trimester women had lower 25(OH)D levels than third-trimester women (80 nmol/L), likely from shorter duration of supplement use. CONCLUSION Adolescent and adult women of childbearing age have a high prevalence of vitamin D insufficiency. Current prenatal multivitamins (400 IU vitamin D) helped to raise serum 25(OH)D levels, but higher doses and longer duration may be required.

Children with a higher RSV genomic load had a higher risk for more-severe bronchiolitis.