After control measures have begun, active surveillance is continued mainly to answer which question?

1. Putting control measures in place is not the end of an investigation, because there is no guarantee they will work. 2. Continued active surveillance shows whether new cases are slowing, stopping or still appearing. 3. Cases spread across the whole area suggest the measures are generally ineffective; cases in pockets suggest some areas were missed. 4. Surveillance also shows whether the outbreak has moved outside the area the measures targeted. 5. Verifying the diagnosis belongs to Step 3 and is settled long before this point. _Source: CDC Principles of Epidemiology in Public Health Practice, 3rd Edition, section Step 12 Initiate or Maintain Surveillance_