Table 4.
Estimates of and factors associated with serial interval based on 558 infector-infectee pairs.
| Factors | Pairs, n (%) | Subgroup-specific estimates (95% empirical CI) | Percentage contribution (95% CI) | ||||
| Age group of infector (years) | |||||||
|
|
0-30 | 77 (13.8) | 4.12 (3.41, 4.83) | Referencec | |||
|
|
31-45 | 121 (21.7) | 4.43 (3.53, 5.33) | –0.24 (–16.50, 17.88) | |||
|
|
46-60 | 179 (32.1) | 4.84 (4.26, 5.43) | 10.47 (–6.17, 28.92) | |||
|
|
≥61 | 181 (32.4) | 5.12 (4.42, 5.82) | 7.57 (–9.28, 26.33) | |||
| Sex of infector | |||||||
|
|
Female | 295 (52.9) | 4.83 (4.34, 5.33) | Referencec | |||
|
|
Male | 263 (47.1) | 4.64 (4.10, 5.18) | –5.52 (–14.81, 4.37) | |||
| Presence of chronic conditions among infectors | |||||||
|
|
No | 485 (86.9) | 4.58 (4.20, 4.95) | Referencec | |||
|
|
Yes | 73 (13.1) | 5.85 (4.57, 7.13) | 0.41 (–15.17, 17.67) | |||
| Number of general symptoms presented by infectors | |||||||
|
|
0 | 338 (60.6) | 4.78 (4.32, 5.25) | Referencec | |||
|
|
≥1 | 220 (39.4) | 4.69 (4.09, 5.28) | –6.34 (–16.48, 4.53) | |||
| Number of respiratory symptoms presented by infectors | |||||||
|
|
0 | 336 (60.2) | 4.22 (3.83, 4.61) | Referencec | |||
|
|
≥1 | 222 (39.8) | 5.54 (4.84, 6.23) | 8.29 (–3.07, 20.48) | |||
| Type of setting | |||||||
|
|
Household | 390 (69.9) | 4.83 (4.41, 5.25) | Referencec | |||
|
|
Institution | 10 (1.8) | 5.00 (2.59, 7.41) | 4.05 (–30.27, 47.56) | |||
|
|
Social activity | 113 (20.3) | 4.27 (3.54, 4.99) | –9.17 (–20.78, 3.41) | |||
|
|
Work | 45 (8.1) | 5.16 (3.12, 7.19) | –4.00 (–21.02, 15.12) | |||
| Wave | |||||||
|
|
1 | 94 (16.8) | 6.70 (5.45, 7.95) | Referencec | |||
|
|
2 | 464 (83.2) | 4.35 (4.00, 4.70) | –33.90 (–45.08, –21.63) | |||
| Order of transmission | |||||||
|
|
Secondary | 445 (79.7) | 4.89 (4.49, 5.30) | Referencec | |||
|
|
Tertiary | 102 (18.3) | 4.36 (3.46, 5.27) | –17.31 (–28.84, –4.75) | |||
|
|
Quaternary or beyond | 11 (2) | 2.18 (–0.52, 4.88) | –50.75 (–72.53, –23.45) | |||
| Relative mobility indexa,b,c | N/Ad | N/A | 0.83 (0.32, 1.33) | ||||
aAn 8-day lag was assumed to account for the time between exposure to SARS-CoV-2 and the first symptom onset, based on the estimated 7.76-day incubation period [21].
bThe original mobility index was further adjusted relative to January 18, 2020, which has a value of 100.
cThe reference is a common comparator across all variables.
dN/A: not applicable.