Applying infectious disease forecasting to public health: a path forward using influenza forecasting examples.

BACKGROUND: Infectious disease forecasting aims to predict characteristics of both seasonal epidemics and future pandemics. Accurate and timely infectious disease forecasts could aid public health responses by informing key preparation and mitigation efforts. MAIN BODY: For forecasts to be fully integrated into public health decision-making, federal, state, and local officials must understand how forecasts were made, how to interpret forecasts, and how well the forecasts have performed in the past. Since the 2013-14 influenza season, the Influenza Division at the Centers for Disease Control and Prevention (CDC) has hosted collaborative challenges to forecast the timing, intensity, and short-term trajectory of influenza-like illness in the United States. Additional efforts to advance forecasting science have included influenza initiatives focused on state-level and hospitalization forecasts, as well as other infectious diseases. Using CDC influenza forecasting challenges as an example, this paper provides an overview of infectious disease forecasting; applications of forecasting to public health; and current work to develop best practices for forecast methodology, applications, and communication. CONCLUSIONS: These efforts, along with other infectious disease forecasting initiatives, can foster the continued advancement of forecasting science.

Reduced Severity of Pertussis in Persons With Age-Appropriate Pertussis Vaccination-United States, 2010-2012.

BACKGROUND: In 2012, >48000 pertussis cases were reported in the United States. Many cases occurred in vaccinated persons, showing that pertussis vaccination does not prevent all pertussis cases. However, pertussis vaccination may have an impact on disease severity. METHODS: We analyzed data on probable and confirmed pertussis cases reported through Enhanced Pertussis Surveillance (Emerging Infections Program Network) between 2010 and 2012. Surveillance data were collected through physician and patient interview and vaccine registries. We assessed whether having received an age-appropriate number of pertussis vaccines (AAV) (for persons aged ≥3 months) was associated with reduced odds of posttussive vomiting, a marker of more clinically significant illness, or of severe pertussis (seizure, encephalopathy, pneumonia, and/or hospitalization). Adjusted odds ratios were calculated using multivariable logistic regression. RESULTS: Among 9801 pertussis patients aged ≥3 months, 77.6% were AAV. AAV status was associated with a 60% reduction in odds of severe disease in children aged 7 months-6 years in multivariable logistic regression and a 30% reduction in odds of posttussive vomiting in persons aged 19 months-64 years. CONCLUSIONS: Serious pertussis symptoms and complications are less common among AAV pertussis patients, demonstrating that the positive impact of pertussis vaccination extends beyond decreasing risk of disease.

Impact of Routine Quantiferon Testing on Latent Tuberculosis Diagnosis and Treatment in Refugees in Multnomah County, Oregon, November 2009-October 2012.

Interferon-gamma release assays have potentially been transformative to screening programs focused on latent tuberculosis infection (LTBI) in foreign-born persons. We sought to add to this assessment by presenting the impact of a well-established refugee screening and treatment program switching from skin testing to Quantiferon(®)-TB Gold (QFT). We completed a retrospective cohort of refugees screened for tuberculosis between November 1, 2009-April 30, 2011 (pre-QFT) and May 1, 2011-October 31, 2012 (post-QFT). Among 2244 refugees screened that met the inclusion criteria, there was a significant difference in the proportion of refugees diagnosed with LTBI between the two time periods (p = <0.0001). In multivariate analysis, refugees tested with QFT had a greater odds of treatment initiation (adjusted odds ratio 1.53; 95% CI 1.02-2.29, p = 0.040). However, test type had no impact on treatment completion (odds ratio 0.88; 95% CI 0.57-1.36, p = 0.560). Although we demonstrated increased efficiency in LTBI diagnosis in this group, treatment completion rates indicate other barriers to treatment that must be addressed.

Vaccinated children and adolescents with pertussis infections experience reduced illness severity and duration, Oregon, 2010-2012.

BACKGROUND: Bordetella pertussis causes severe respiratory illness among infants and adolescents. High proportions of breakthrough infection have been observed. To understand the effect of vaccination in the era of acellular pertussis vaccines (DTaP and Tdap), we assessed if vaccination status is associated with disease severity and duration. METHODS: The Multnomah County Health Department conducts enhanced pertussis surveillance for 1.7 million residents in the Portland, Oregon, metropolitan area. Surveillance activities include ascertaining demographics, clinical presentation, cough duration, vaccination history, and other health outcomes. Utilizing Advisory Committee on Immunization Practices (ACIP) routine vaccination recommendations, we analyzed a cohort of persons aged 6 weeks to 18 years with confirmed pertussis to assess illness severity and duration by vaccination status. Analysis was conducted using both logistic regression (disease severity) and survival analysis (cough duration). RESULTS: During 2010-2012, 98.7% (n = 624) of patients with confirmed pertussis in our cohort had vaccination, treatment, demographic, and outcome information. Among these patients, 45% (n = 286) were ACIP up to date with vaccinations. Ever-vaccinated cases were significantly less likely to be hospitalized or develop severe illness (adjusted odds ratio [aOR], 0.2; 95% confidence interval [CI], .1-.8 and aOR, 0.4; 95% CI, .2-.9, respectively). ACIP up-to-date patients stopped coughing significantly more rapidly than unvaccinated patients (adjusted hazard ratio, 1.7; 95% CI, 1.3-2.2). CONCLUSIONS: Patients with pertussis vaccination had decreased morbidity characterized by less severe illness and significantly reduced illness duration. Therefore, vaccination is recommended among at-risk individuals, and research into the nature of the residual vaccine immunity is warranted.

Urban trees and the risk of poor birth outcomes.

This paper investigated whether greater tree-canopy cover is associated with reduced risk of poor birth outcomes in Portland, Oregon. Residential addresses were geocoded and linked to classified-aerial imagery to calculate tree-canopy cover in 50, 100, and 200 m buffers around each home in our sample (n=5696). Detailed data on maternal characteristics and additional neighborhood variables were obtained from birth certificates and tax records. We found that a 10% increase in tree-canopy cover within 50 m of a house reduced the number of small for gestational age births by 1.42 per 1000 births (95% CI-0.11-2.72). Results suggest that the natural environment may affect pregnancy outcomes and should be evaluated in future research.