On December 13, 2007, certain lots of the Hib vaccine made by Merck & Co. were recalled. Although the vaccines are safe, Merck couldn’t guarantee that the recalled lots were completely sterile because there was a remote possibility that a type of bacteria called B. cereus was on the equipment when the vaccine was manufactured. As a result of the recall, the vaccine is in short supply. The CDC is advising pediatricians to temporarily stop giving the booster dose (given at 12 to 15 months of age) to healthy children. Supplies should be replenished by late 2008, says Dr. Offit.