Table 4 Factors affecting the length of serial intervals and the acceleration factors estimated with a multiple parametric model

Primary cases

  Primary school

118

Ref.

  Junior high school

44

1.29

(1.05–1.59)

Secondary cases

  Preschool

22

0.77

(0.55–1.08)

  Primary school

31

0.75

(0.55–1.08)

  Junior high school

20

0.60

(0.43–0.85)

  High school

2

0.71

(0.31–1.66)

  Father

26

Ref.

  Mother

39

0.86

(0.64–1.15)

Grandparents and other adults

22

0.93

(0.66–1.30)

Antiviral prescription for primary cases

150

0.81

(0.56–1.18)

Vaccination for primary cases

80

1.06

(0.89–1.27)

Absence interval of primary cases

≤3 days

42

Ref.

3 - 7 days

102

1.13

(0.91-1.40)

>7 days

17

1.74

(1.25-2.42)