Volume 27, Number 5—May 2021
Dispatch
SARS-CoV-2 Serial Interval Variation, Montana, USA, March 1–July 31, 2020
Isaiah G. Reed
, Ethan S. Walker, and Erin L. Landguth
, Ethan S. Walker, and Erin L. Landguth
Table 2
Sensitivity analyses: forward and backward severe acute respiratory syndrome coronavirus 2 serial interval estimates by nonpharmaceutical intervention subperiod and length of intervention effects delay*
| SI estimate method | NPI subperiod | Measure | Sensitivity analysis scenarios† |
||
|---|---|---|---|---|---|
| No delay | 1-week delay | 2-week delay | |||
| Forward: onset of
primary case |
Pre–shelter-in-place, Mar 1–27 |
No. pairs | 95 | 105 | 113 |
| Mean SI (95%CI) | 6.84 (5.84–7.87) | 6.83 (5.67–8.07) | 6.66 (5.61–7.80) | ||
| SD (95% CI) |
5.56 (4.45–6.80) |
5.78 (4.48–7.24) |
5.61 (4.50–6.84) |
||
| Shelter-in-place, Mar 28–Apr 25 |
No. pairs | 20 | 10 | 3 | |
| Mean SI (95% CI) | 5.54 (3.34–8.26) | 4.08 (2.61–5.85) | 2.46 (1.24–4.10) | ||
| SD (95% CI) |
5.30 (2.69–8.76) |
2.83 (1.47–4.66) |
1.52 (0.38–3.38) |
||
| Reopening, phase 1, Apr 26–May 31 |
No. pairs | 25 | 64 | 114 | |
| Mean SI (95% CI) | 5.26 (3.64–7.21) | 7.45 (6.02–9.02) | 7.10 (6.08–8.16) | ||
| SD (95% CI) |
4.74 (2.86–7.09) |
6.24 (4.70–8.03) |
5.82 (4.77–6.99) |
||
| Reopening, phase 2, Jun 1–30 |
No. pairs | 248 | 296 | 289 | |
| Mean SI (95% CI) | 6.23 (5.59–6.85) | 5.39 (4.88–5.94) | 5.08 (4.56–5.59) | ||
| SD (95% CI) |
5.32 (4.61–6.05) |
4.59 (4.01–5.21) |
4.32 (3.75–4.94) |
||
| Reopening, phase 2, Jul 1–31 |
No. pairs | 195 | 117 | 76 | |
| Mean SI (95% CI) | 4.42 (3.92–4.93) | 4.20 (3.65–4.78) | 3.98 (3.36–4.67) | ||
| SD (95% CI) |
3.51 (2.97–4.06) |
3.20 (2.65–3.80) |
2.90 (2.29–3.60) |
||
| Backward: onset of secondary case | Pre–shelter-in-place, Mar 1–27 |
No. pairs | 61 | 89 | 105 |
| Mean SI (95% CI) | 4.82 (3.88–5.84) | 5.83 (4.86–6.82) | 6.48 (5.55–7.51) | ||
| SD (95% CI) |
3.84 (2.88–4.93) |
4.91 (3.86–6.08) |
5.50 (4.44–6.63) |
||
| Shelter-in-place, Mar 28–Apr 25 |
No. pairs | 54 | 26 | 11 | |
| Mean SI (95% CI) | 8.57 (6.77–10.58) | 9.03 (6.73–11.66) | 7.58 (4.29–11.83) | ||
| SD (95% CI) |
6.95 (5.10–8.99) |
6.52 (4.28–9.22) |
6.21 (2.91–10.73) |
||
| Reopening, phase 1, Apr 26–May 31 |
No. pairs | 19 | 30 | 62 | |
| Mean SI (95% CI) | 3.79 (2.46–5.37) | 4.95 (3.53–6.60) | 4.57 (3.64–5.60) | ||
| SD (95% CI) |
3.10 (1.70–4.90) |
4.41 (2.78–6.43) |
3.73 (2.72–4.90) |
||
| Reopening, phase 2, Jun 1–30 |
No. pairs | 202 | 280 | 310 | |
| Mean SI (95% CI) | 5.38 (4.72–6.08) | 5.14 (4.64–5.67) | 5.22 (4.73–5.77) | ||
| SD (95% CI) |
4.59 (3.86–5.41) |
4.31 (3.77–4.90) |
4.38 (3.85–4.97) |
||
| Reopening, phase 2, Jul 1–31 | No. pairs | 233 | 161 | 106 | |
| Mean SI (95% CI) | 5.43 (4.85–6.05) | 5.82 (5.12–6.56) | 6.45 (5.37–7.57) | ||
| SD (95% CI) | 4.52 (3.90–5.17) | 4.88 (4.14–5.70) | 5.41 (4.35–6.64) | ||
*NPI, nonpharmaceutical intervention; SI, serial interval. †Serial interval estimation methods and delay scenarios contain dissimilar pair totals because of their temporal differences (forward pairs, n) no delay: 583; 1-week delay: 592; 2-week delay: 595; (backward pairs, n) no delay: 569; 1-week delay: 586; 2-week delay: 594.
Page created: March 09, 2021
Page updated: April 22, 2021
Page reviewed: April 22, 2021
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