The last reported case is not always the last infection
The most recent report may concern an illness that began days earlier. A newly infected person may not yet have symptoms or appear in the system. The timeline therefore needs more than the date the dashboard last changed.
Ask what evidence supports closure
- Has the likely source or transmission route been addressed?
- Has an appropriate observation period passed?
- Is case-finding sufficiently complete?
- Are pending tests or unresolved reports accounted for?
- What disease-specific guidance applies?
There is no single number of case-free days that fits every outbreak.
Administrative closure and zero risk differ
An investigation may close under defined criteria while some background risk remains. Communicating that distinction prevents “over” from being interpreted as a guarantee that no future case can occur.
Keep the learning after closure
Document the evidence, remaining uncertainties, response actions, and opportunities to improve surveillance. If new information appears, the conclusion may need review.
The useful public statement explains which criteria were met and what monitoring continues. That is more informative than declaring success solely because recent bars on a provisional chart are low or because no one has submitted another report.
