Table 2.
Summary of outbreak characteristics in primary and secondary representative schools used in quanta generation rate (q) back-calculation process
| 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 |
aBased on the information reported in Riley et al. (1978) and Chen et al. (1989) case studies [22, 33]
bAssuming similar lunchtime as Chen et al. (1989) [22] case study ± 50%
cFor the primary estimate we considered the reported removal efficiency in Riley et al. (1978) [33]
dAzimi and Stephens (2013), Table 4; assuming MERV4 and MERV 7 for the air filters [54]
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%)
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
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
hU.S. Department of Energy commercial reference building models of the national building stock, [48]; Table A-2, primary and secondary education buildings