Vaccination of children following a previous hypotonic-hyporesponsive episode

Background: Hypotonic-hyporesponsive episodes (HHE) were once considered a contraindication to pertussis vaccination. Methodology: To evaluate the safety of further vaccination, chart review wa s conducted of 66 children who had experienced an HHE, and who were assesse d in one of three special clinics in three capital city tertiary paediatric hospitals. Immediately prior to the HHE, 63 children had received whole-ce ll pertussis vaccine, three had received acellular pertussis vaccine. Results: Sixty-four of the 66 children were vaccinated in the special clini c, 59 with pertussis-containing vaccines (55 acellular, four whole-cell), w ithout serious adverse events. There were no HHE after these further vaccin ations. Conclusions: Previously healthy children who experience HHE reactions can s afely continue standard vaccination schedules.