The Oregon Child Absenteeism Due to Respiratory Disease Study (ORCHARDS): Rationale, Objectives, and Design

Abstract

Background: Influenza viruses pose significant disease burdens through annual seasonal outbreaks and unpredictable pandemics. Existing influenza surveillance programs have relied heavily on medical facility reporting influenza. Continuously monitoring cause-specific school absenteeism may identify local activity acceleration of seasonal influenza. The Oregon Child Absenteeism Due to Respiratory Disease Study (ORCHARDS) implements daily school-based monitoring of influenza-like illness-specific student absenteeism (a-ILI) in pre-kindergarten through grade 12 schools and assesses this approach for early detection of accelerated influenza and other respiratory pathogen transmission in schools and surrounding communities. Methods: Starting in September 2014, ORCHARDS has combined reporting of daily absenteeism though automated processes within six schools and home visits to school children with acute respiratory infections (ARI). Demographic, epidemiological and symptom data are collected along with respiratory specimens. Specimens are tested for influenza and other respiratory viruses. Household members may participate in a supplementary household transmission study. Community comparisons are made possible using a pre-existing, long-standing, and highly effective influenza surveillance program, based on medically attended influenza at five primary care clinics in the same geographical area. Results: Over the first five years, a-ILI accounted for 6,634 (0.20%) of 3,260,461 student school days. Viral pathogens were detected in 64.5% of 1,728 children visited at home with ARI. Influenza was the most commonly detected virus, noted in 23.3% of ill students. Influenza (p<0.001) and adenovirus (P=0.004) were significantly associated with positive likelihoods of a-ILI. Discussion: ORCHARDS uses a community-based design to detect and evaluate influenza trends over multiple seasons and to evaluate the utility of absenteeism for early detection of accelerated influenza and other respiratory pathogen transmission in schools and surrounding communities.