Merck Announces Voluntary Recall of Certain Vaccines

WHITEHOUSE STATION, N.J., December 12, 2007 - Merck & Co., Inc. announced today that the Company has initiated a voluntary recall of 11 lots of its Haemophilus influenzae type B vaccine, PEDVAXHIB [Haemophilus b Conjugate Vaccine (Meningococcal Protein Conjugate)], and two lots of its combination Haemophilus influenzae type B/ hepatitis B vaccine, COMVAX [Haemophilus b Conjugate (Meningococcal Protein Conjugate)]. The recall is specific to these 13 lots and does not affect any other vaccines manufactured by Merck. The affected doses of PEDVAXHIB and COMVAX were distributed starting in April 2007.

Merck is conducting this recall because it can not assure sterility of these specific vaccine lots. The potential contamination of these specific lots was identified as part of the Company's standard evaluation of its manufacturing processes. Sterility tests of the vaccine lots that are the subject of this recall have not found any contamination in the vaccine.

The potential for contamination of any individual vaccine is low, and, if present, the level of contamination would be low. However, because the Company cannot assure the sterility of these specific lots of vaccine, it is conducting this recall.

Merck is working closely with the U.S. Food and Drug Administration (FDA) and the U.S. Centers for Disease Control and Prevention (CDC) to inform affected healthcare providers of this recall. We are also in the process of communicating with public health authorities and healthcare providers in the U.S. and in other countries where these lots were distributed, as appropriate.

"We are taking this action because we are committed to ensuring the quality of our vaccines," said Mark Feinberg, M.D., Ph.D., vice president, Medical and Policy Affairs, Merck Vaccines and Infectious Diseases. "We know that our vaccines can play an important role in the nation's public health system, and we are committed to resolving this issue as quickly as possible to ensure that our vaccines are readily available."

Physicians are advised not to administer any vaccine from the vaccine lots being recalled. Individuals who received vaccine from these lots should complete their immunization series with a Haemophilus b conjugate-containing vaccine not affected by this recall, but do not need to be revaccinated to replace a dose they received from a recalled lot. The efficacy of the vaccine was not affected.