In the UK, a health protection incident may be defined as [12]: - “an incident in which two or more people experiencing a similar illness are linked in time or place” - “a greater than expected rate of infection compared with the usual background rate for the place and time where the incident has occurred” - “a single case for certain rare diseases” | A NCD “incident” definition proposed by the authors as comprising: - a significant and sustained step changed deterioration in population outcomes in comparison to the baseline trend or comparator And - the individuals or populations have similar conditions or have accessed the same health system and are linked in time or place And there is - potential for single cause or focus of variation |