The child may have only received diluent instead of HIB reconstituted with diluent. There were three patients of which may have been affected. Two received appropriately prepared HIB vaccines and one received diluent. It is unclear which patient of the three received only diluent. No adverse reactions have occurred since the time of administration. The dose is planned to be repeated during the child’s 18 month visit to ensure proper vaccination, and the child will be monitored for any reactions at that time. Parents have been notified and expressed understanding of the situation and have no further concerns.