A region where community transmission was identified within the last 14 days.
A region where there is no community transmission within the last 14 days but shares a border with a red zone.
A region where there is no community transmission within the last 14 days; if new cases do arise, they should be already in isolation. Additionally, a green zone shares no borders with a red zone.
Surveillance of possible outbreaks
Once achieving zero community transmission in a given region, maintaining its green/yellow zone status is crucial; these regions are always prone to outbreaks. Contact tracing is a powerful tool used to identify the root of outbreaks and combine geographic data with incidence rates. A public health authority would firstly identify the contact in question; these can be individuals who have tested positive for COVID-19 or those who have been near infected individuals. These contacts are then asked to voluntarily offer a list of further contacts that they came in close contact with along with notable places they visited; they also note valuable information such as the likely date of infection and the day of the onset of symptoms (if any). Moreover, they provide the contacts with necessary information on next steps, whether it be self-isolating, getting tested, or medical care.