Table 1.
Characteristics of the Primary Cases, Household Contacts, and Households
| All Households | Household Group 1a | Household Group 2b | |
|---|---|---|---|
| Households, n | 7,326 | 2,702 | 4,624 |
| Household contacts, n | 17,586 | 8,014 | 9,572 |
| Secondary cases | 4,282 (24.3) | 2,808 (35.0) | 1,474 (15.4) |
| Vaccination status c | |||
| Primary = No / Contact = No | 14,878 (84.6) | 7,299 (91.1) | 7,579 (79.2) |
| Primary = No / Contact =Yes | 1,556 (8.8) | 523 (6.5) | 1,033 (10.8) |
| Primary = Yes / Contact = No | 640 (3.6) | 177 (2.2) | 463 (4.8) |
| Primary = Yes / Contact = Yes | 512 (2.9) | 15 (0.2) | 497 (5.2) |
| Children aged ≤11 years in household | |||
| Yes | 8,014 (45.6) | 8,014 (100.0) | 0 (0.0) |
| Primary case age | |||
| ≥12 years | 13,077 (74.4) | 3,505 (43.7) | 9,572 (100.0) |
| ≤11 years | 4,509 (25.6) | 4,509 (56.3) | 0 (0.0) |
| Contact age and sex | |||
| ≤11 years, male or female | 3,048 (17.3) | 3,048 (38.0) | - |
| 12–19 years, male or female | 2,091 (11.9) | 598 (7.5) | 1,493 (15.6) |
| 20–59 years, male | 4,824 (27.4) | 2,117 (26.4) | 2,707 (28.3) |
| 20–59 years, female | 5,368 (30.5) | 2,251 (28.1) | 3,117 (32.6) |
| ≥60 years, male or female | 2,255 (12.8) | - | 2,255 (23.6) |
| Household size | |||
| 2 | 1,660 (9.4) | - | 1,660 (17.3) |
| 3 | 4,058 (23.1) | 1,360 (17.0) | 2,698 (28.2) |
| 4 | 8,040 (45.7) | 4,302 (53.7) | 3,738 (39.1) |
| 5 | 3,828 (21.8) | 2,352 (29.3) | 1,476 (15.4) |
| Infection month of the primary case | |||
| Jan 2022 | 3,532 (20.1) | 1,540 (19.2) | 1,992 (20.8) |
| Feb 2022 | 6,404 (36.4) | 2,887 (36.0) | 3,517 (36.7) |
| Mar 2022 | 4,806 (27.3) | 2,483 (31.0) | 2,323 (24.3) |
| Apr 2022 | 2,844 (16.2) | 1,104 (13.8) | 1,740 (18.2) |
| Municipality | |||
| City A | 5,457 (31.0) | 2,886 (36.0) | 2,571 (26.9) |
| City B | 12,129 (69.0) | 5,128 (64.0) | 7,001 (73.1) |
Data are presented as n (%) unless otherwise indicated.
a
Household Group 1: Households with ≥1 children aged ≤11 years.
b
Household Group 2: Households with all members aged ≥12 years. c “Primary” refers to the primary case, and “Contact” refers to the household contact. For vaccination status, “Yes” refers to individuals for whom seven days had passed after receiving a third COVID-19 vaccine dose; all other individuals were designated “No”.