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Table 2 Summary of outbreak characteristics in primary and secondary representative schools used in quanta generation rate (q) back-calculation process

From: Estimating the nationwide transmission risk of measles in US schools and impacts of vaccination and supplemental infection control strategies

Parameter Primary School
Best-Estimate [Range]
Secondary School
Best-Estimate [Range]
Reference
No. of enrolled students during outbreaks 868 1873 Literaturea
No. of first generation infected cases 28 69 Literaturea
No. of index case/s 1 1 Literaturea
Infection period in school (day) 3 4 Literaturea
Portion of unvaccinated students 3.3% 0.3% Literaturea
Portion of students with 1-dose vaccination 96.7% 70.9% Literaturea
Portion of students with 2-dose vaccination 0.0% 28.8% Literaturea
No. of students in infector’s classroom 24 30 Literaturea
No. of students in recirculation area 592 1843 Literaturea
No. of students in common area 664 1873 Literaturea
Average time spent in classroom/s (min) 280 [270–290]b 340 Literaturea
Average time spent in recirculation area (min) 280 [270–290]b 340 Literaturea
Average time spent in common area (min) 20 [10–30]b 70 Literaturea
HVAC system runtime fraction 1 0.768 Literaturea
Recirculated air fraction 0.438 0.05 Literaturea
Supply airflow rate of one classroom (m3/min) 28.3 8.5 Literaturea
Total HVAC system capacity (m3/min) 1019.4 595 Literaturea
Air filter removal efficiency (%) 12 12c [10.5–42.2] Literatured
Occupancy density of classroom (m2/person) 4 [3–5] 4 [3–5] DOEe
Volume of recirculation area (m3) 13,832 [10374–17,290] 33,600 [25200–42,000] Estimatedf
Occupancy density of common area (m2/person) 1.39 [1.04–1.74] 1.39 [1.04–1.74] DOEe
Inhalation rate (m3/day) 12.96[11.34–14.53] 15.53 [13.93–17.45] EPAg
Deposition rate of measles bio-aerosols (1/h) 1.7 [1.0–2.7] 1.7 [1.0–2.7] Literatured
Natural ventilation rate (1/h) 0.31 [0.12–0.49] 0.31 [0.12–0.49] DOEh
  1. aBased on the information reported in Riley et al. (1978) and Chen et al. (1989) case studies [22, 33]
  2. bAssuming similar lunchtime as Chen et al. (1989) [22] case study ± 50%
  3. cFor the primary estimate we considered the reported removal efficiency in Riley et al. (1978) [33]
  4. dAzimi and Stephens (2013), Table 4; assuming MERV4 and MERV 7 for the air filters [54]
  5. eU.S. Department of Energy commercial reference building models of the national building stock report, [48]; the average density of students in educational buildings (±25%)
  6. fFor the elementary school estimated based on the HVAC total capacity versus supply air flow of each classroom and for the high school calculated based on the of occupancy density of classrooms and the school’s floor plan
  7. gU.S. Environmental Protection Agency (EPA), [63]; Interpolated from the reported inhalation rates of children in various age ranges in the Exposure Factors Handbook: 2011 Edition, Table 6.23
  8. hU.S. Department of Energy commercial reference building models of the national building stock, [48]; Table A-2, primary and secondary education buildings