Med Headlines - A vaccine shortage has prompted physicians to defer administration of the routine Hib booster vaccine booster in healthy children. According to the American Academy of Pediatrics, the vaccine is typically administered to all children at age 12-15 months, but new guidelines recommend administering the vaccine only to specific, high risk groups.

CDC officials are encouraging health care professionals to track children in whom the booster dose is deferred so they can be recalled for immunization when the Hib supply disruption improves. The interim recommendations are outlined in the Morbidity and Mortality Weekly Report released by the CDC.

The shortage can be traced to a voluntary recall by Merck on December 13 involving two of its Hib-containing vaccine products. Specifically, the company recalled 10 lots of its monovalent Hib conjugate vaccine, sold as PedavaxHIB and two lots of its combination Hib/hepatitis B vaccine, sold as COMVAX.

The products were recalled because Merck announced that it could not assure the sterility of the manufacturing equipment used to produce those lots leading to concerns about potential product contamination. In all, about one million doses of vaccine were recalled, including about one-half of the doses contained in the CDC national stockpile.

Merck has suspended production of its Hib conjugate vaccines and does not expect to resume distribution of these vaccines until the fourth quarter of 2008. The CDC is urging health care professionals left with little or no useable Hib vaccine to order only the number of doses required to fulfill the needs of their patients.