Table 1.
Dominant influenza types and subtypes across six influenza seasons, along with outbreak severity and timing.
Fig 1.
Flow diagram of absenteeism data from telephone reporting by parents/guardians, to entry into the student information system at the Oregon School District, to data transfer to the ORCHARDS research team.
Fig 2.
Location of the Oregon School District (OSD) in the villages of Oregon and Brooklyn in South Central Wisconsin.
The red dots depict locations of family medicine clinics that participate in long-term surveillance of medically-attended influenza.
Fig 3.
Total absentee counts, by grade level, across entire study for a-ILI, a-I and a-TOT.
Defined types of absenteeism: a-TOT = absent for any reason; a-I = absent due to illness; a-ILI = absent due to influenza-like illness.
Table 2.
School enrollment estimates and student absenteeism by defined type* and school year—Oregon School District, Dane County, Wisconsin: 2014–2020.
Table 3.
Acute respiratory infection (ARI) cases evaluated and numbers of influenza A and B cases detected across six influenza seasons at five influenza surveillance clinics,* Dane County, Wisconsin.
Fig 4.
Numbers of daily student absences in each of three categories (a-TOT = absent for any reason, a-I = absent due to illness and a-ILI = absent due to influenza-like illness) and number of all-age medically-attended influenza (MAI) cases in surrounding communities during six school years/influenza seasons.
The black line is the estimated mean number of daily events from a generalized additive quasi-Poisson regression model with calendar date (thin-plate spline) and day of week (dummy variables) as predictors. Gaps in the fitted curves represent breaks in the school calendar.
Table 4.
Characteristics of 2,378 ORCHARDS student participants in the home study.
Table 5.
Relationship between influenza laboratory detection and absence with influenza-like illness (a-ILI) in a cohort of students visited at home.
Fig 5.
Cross-correlation functions (estimate and 95% confidence interval) for square-root daily absenteeism counts and square-root medically-attended influenza (MAI) counts for all six school years/influenza seasons combined (top row) and for each school year/influenza season.
Results are shown for total absenteeism (a-TOT; first column), absenteeism due to illness (a-I; second column) and absenteeism due to influenza-like illness (a-ILI; third column). Negative lag/lead indicates absenteeism preceding MAI, while positive lag/lead indicates MAI preceding absenteeism. The maximal correlation for absenteeism preceding MAI is highlighted in blue; if different, the maximum correlation over the entire time frame (-14 days to +14 days) is highlighted in red.