TABLE 2. Rates of secondary laboratory-confirmed SARS-CoV-2 infections among household members enrolled in a prospective study of SARS-CoV-2 household transmission — Tennessee and Wisconsin, April–September 2020.
| Characteristic | Laboratory-confirmed SARS-CoV-2 infections/Household members at risk | Secondary infection rate % (95% CI)* |
|---|---|---|
|
All household members
|
102/191 |
53 (46–60) |
|
Nasal swab–positive tests only
|
89/191 |
47 (40–54) |
|
RT-PCR–negative at enrollment
|
48/137 |
35 (28–43) |
|
Index patient age group, yrs
| ||
| <12 |
9/17 |
53 (31–74) |
| 12–17 |
11/29 |
38 (23–56) |
| 18–49 |
64/116 |
55 (46–64) |
| ≥50 |
18/29 |
62 (44–77) |
|
Index patient sex
| ||
| Female |
66/108 |
61 (52–70) |
| Male |
36/83 |
43 (33–54) |
|
Index patient race/ethnicity
| ||
| White, non-Hispanic |
71/139 |
51 (43–59) |
| Other race, non-Hispanic |
9/17 |
53 (31–74) |
| Hispanic or Latino |
22/35 |
63 (46–77) |
|
Household member age group, yrs
| ||
| <12 |
18/32 |
57 (39–72) |
| 12–17 |
14/30 |
47 (30–64) |
| 18–49 |
54/92 |
59 (48–68) |
| ≥50 |
16/37 |
43 (29–59) |
|
Household member sex
| ||
| Female |
52/103 |
50 (41–60) |
| Male |
50/88 |
57 (46–67) |
|
Household member race/ethnicity
| ||
| White, non-Hispanic |
67/127 |
53 (44–61) |
| Other race, non-Hispanic |
9/24 |
38 (21–57) |
| Hispanic or Latino |
26/40 |
65 (50–78) |
|
Household size, no. of persons
| ||
| 2 |
26/38 |
68 (53–81) |
| 3 |
25/41 |
61 (46–74) |
| 4 |
18/40 |
45 (31–60) |
| ≥5 | 33/72 | 46 (35–57) |
Abbreviations: CI = confidence interval; RT-PCR = reverse transcription–polymerase chain reaction.
* Secondary infection rate, and 95% CI, estimated over 7 days of follow-up. Enrolled household members who did not report symptoms at time of illness onset in the index case-patient were considered at risk.