COVID-19 transmission scenarios and implementation of CT activities, from the WHO guidance for contact tracing, 1 February 20216
| Epidemiological scenario | CT activities |
| No cases | Identifying and training existing personnel and preparing them for deployment and response. |
| Sporadic cases | Exhaustive strategies should be implemented. Case investigation for all cases is necessary for timely suppression of transmission. |
| Clusters | CT is required to suppress transmission within clusters and recognise events that contribute to transmission. These events can be mitigated by different Public Health and Social Measures. |
| Community transmission (including four subcategories of increasing incidence) | Despite challenges, CT remains crucial, particularly in high incidence scenarios. CT should continue and focus on high-risk exposure contacts in accordance with the available capacities |