Table 5. Pooled estimates of secondary attack rates, only high and moderate quality studies.
First Author | Number of Index Patients | Type of Contacts Traced in Study | Contacts | Secondary Attack Rate | |
---|---|---|---|---|---|
Number of Contacts Tested | Number of Contacts Testing Positive | (95% CI)† | |||
Park, S. | 4° | Household Contacts Only | 11 | 0 | 0% |
(0% to 28.5%) | |||||
Park, S. | 4°° | Household Contacts Only | 4 | 0 | 0% |
(0% to 60.2%) | |||||
Ye, F. | 1° | Close Contacts | 44 | 4 | 9.1% |
(2.5% to 21.7%) | |||||
Huang, L. | 1° | Close Contacts | 22 | 7 | 31.8% |
(13.9% to 54.9%) | |||||
Li, P. | 1° | Household Contacts Only | 5 | 4 | 80% |
(28.4% to 99.5%) | |||||
Xiao, W. | 2° | Household and Close Contacts | 10 | 3 | 30% |
(6.7% to 65.2%) | |||||
Simple Pooled Estimate | 13 | 96 | 18 | 18.8%* |
Abbreviations: 95% CI, 95% confidence interval.
*Estimates have been simply pooled to facilitate interpretation of the body of evidence. Since studies are too heterogeneous in methods of contact tracing, confidence intervals on these estimates have not been calculated to not overstate any sense of precision.
°Index patients were pre-symptomatic (exposure occurred prior to symptom onset).
°°Index patients remained asymptomatic.
†Confidence intervals calculated for individual studies only, using the Clopper-Pearson exact method.