Recognising and responding to outbreaks of hepatitis A associated with child day-care centres

Objectives: To assess the appropriateness of a protocol for recognising and responding to outbreaks of hepatitis A in child day-care centres and to determine if measles-mumps-rubella (MMR) vaccine was given too soon following the administration of normal human immunoglobulin (NIGH) to young children to control the outbreaks. Design: Prospective surveillance to recognise cases of hepatitis A associated with, and outbreaks of hepatitis A in, daycare centres. Main outcome measures: The percentage of initial (`sentinel') cases of hepatitis A associated with day-care centres that were subsequently recognised as also being `index' cases of outbreaks of hepatitis A in the centres, and the number of children 913 months of age when given NIGH who were subsequently given MMR less than three months later. Results: Only 18 (16%) of the 114 sentinel day-care associated cases of hepatitis A were also index cases of outbreaks of hepatitis A in their respective centres. A total of 105 cases of hepatitis A were associated with the 18 outbreak centres; NIGH was administered to 928 (78%) of the attendee children, and to 105 (82%) of the susceptible staff, at the 18 centres. Three of the five children 9-13 months of age when given NIGH were given MMR less that three months later. Conclusions: Although outbreaks of hepatitis A were common events in daycare centres in north Queensland during the two-year study period, a single case of hepatitis A associated with a centre was a poor predictor of an outbreak within that centre. Precautions must be taken to ensure that live vaccines are not administered to young children too soon after NIGH.