TABLE 1.
Rates of Secondary Laboratory-Confirmed SARS-CoV-2 Infection Among Household Contacts (n = 50), Overall and by Characteristic—Los Angeles County, December 2020 to February 2021
| Characteristic | Laboratory-Confirmed SARS-CoV-2 Infections/Household Members at Risk, n/N | SAR % (95% CI) | P |
|---|---|---|---|
| All household contacts | 17/50 | 34 (22–48) | |
| Negative baseline PCR‡ | 6/37 | 16 (8–31) | |
| Index case age group, yr | 0.42 | ||
| ≤5 | 13/33 | 39 (25–56) | |
| 6–17 | 4/17 | 24 (10–47) | |
| Index case sex | 0.16 | ||
| Female | 6/26 | 23 (11–42) | |
| Male | 11/24 | 46 (28–65) | |
| Household member age group, yr | 0.04* | ||
| ≤17 | 2/18 | 11 (3–33) | |
| 18–64 | 15/32 | 47 (31–64) | |
| Household member sex | 0.55 | ||
| Female | 10/25 | 40 (23–59) | |
| Male | 7/25 | 28 (14–48) | |
| Household member is caregiver? | 0.23 | ||
| Yes | 12/28 | 43 (27–61) | |
| No | 5/22 | 23 (10–43) | |
| Home type | 0.41 | ||
| Apartment | 5/10 | 50 (24–76) | |
| House | 12/40 | 30 (18–45) | |
| Number of bedrooms | 0.03* | ||
| <3 | 13/26 | 50 (32–68) | |
| 4+ | 4/24 | 17 (7–36) | |
| Persons-per-room | 0.23 | ||
| ≤0.5 | 6/25 | 24 (11–43) | |
| >0.5 | 11/25 | 44 (27–63) | |
| Index symptomatic at time of testing? | 0.16 | ||
| Yes | 16/40 | 40 (26–55) | |
| No | 1/10 | 10 (2–40) | |
| Index isolated at home? | 0.11 | ||
| Yes | 4/21 | 19 (8–40) | |
| No | 13/29 | 45 (28–62) | |
| Index masked at home? | 0.04* | ||
| Yes | 4/23 | 17 (7–37) | |
| No | 13/27 | 48 (31–66) | |
| Increased hand washing or hand sanitizer use? | 0.01† | ||
| Yes | 6/31 | 19 (9–36) |
*P ≤ 0.05.
†P ≤ 0.01.
‡ Median time of 3 d from index case positivity to baseline household contact test.