Table 2. Contact situations of three infection clusters related with potential pre-symptomatic transmission, Shanghai, China, January–February 2020.
| Cluster | Case | Residence city | Close contact with primary cases (Cases 1A, 2A, 3A) | Time of onset of illness | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Type of contact | Persons | Duration (hours) |
Contact distance (meters) | Contact frequency | Mask wearing | Surroundings | Contact period | ||||
| Cluster 1 | Case 1A | Shanghai | NA | NA | NA | NA | NA | NA | NA | NA | 20 Jan; night |
| Case 1B | Shanghai | Hot pot dinner, mah-jong game | 5 | 6 | < 1 | Frequently within 6 hours | None | Inside a restaurant, a poorly ventilated room | 19 Jan; 17:00 – 23:00 |
22 Jan; 02:00 |
|
| Case 1C | Shanghai | Hot pot dinner, mah-jong game | 5 | 6 | < 1 | Frequently within 6 hours | None | 25 Jan; 09:00 |
|||
| Cluster 2 | Case 2A | Wuhan | NA | NA | NA | NA | NA | NA | NA | NA | 31 Jan; noon |
| Case 2B | Shanghai | Conversation / lunch and dinner | 7 | 11.5 | < 1 | Commonly / frequently | None | In 2C and 2D’s apartment | 21 Jan; 09:30 – 11:00 24 Jan; 09:30 –19:00 |
24 Jan; 19:00 |
|
| Case 2C | Shanghai | Living together with Case 2A | 5 | 241 | < 1 | Frequently | None | In 2C and 2D’s apartment | 21 Jan; night until 2 Feb (isolation) |
31 Jan; noon | |
| Cluster 3 | Case 3A | Wuhan | NA | NA | NA | NA | NA | NA | NA | NA | 20 Jan; 22:00 |
| Case 3B | Shanghai | Living together with Case 3A | 4 | 114 | < 1 | Frequently | None | In their own apartment | 15 Jan; 16:00 until 21 Jan (isolation) |
20 Jan; morning | |
NA: not available.