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

Background Influenza viruses pose significant disease burdens through annual seasonal outbreaks and unpredictable pandemics. Existing influenza surveillance programs have relied heavily on reporting of medically attended influenza (MAI). Continuously monitoring cause-specific school absenteeism may identify local acceleration of seasonal influenza activity. The Oregon Child Absenteeism Due to Respiratory Disease Study (ORCHARDS; Oregon, WI) 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 combined automated reporting of daily absenteeism within 6 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 can opt into a supplementary household transmission study. Community comparisons are possible using a pre-existing, long-standing, and highly effective influenza surveillance program, based on MAI at 5 primary care clinics in the same geographical area. Results Over the first 5 years, a-ILI occurred on 6,634 (0.20%) of 3,260,461 student school days. Viral pathogens were detected in 64.5% of the 1,728 children with ARI who received a home visit. 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 a-ILI. Conclusion ORCHARDS uses a community-based design to detect 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. Initial findings suggest the study design is succeeding in collecting appropriate data to achieve study objectives.