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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