Merck & Co., Inc. said it voluntarily recalled 13 lots of its Hib vaccine given to ankle-biters to prevent meningitis and pneumonia as quality control found production equipment may not have been properly sterilised.

Merck recalled 11 lots of 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.

The company said the recall is 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 US Food and Drug Administration (FDA) and the US Centres for Disease Control and Prevention (CDC) to inform affected healthcare providers of this recall. The company is also communicating with public health authorities and healthcare providers in the US 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, MD, 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, the company officials said in a press statement.

Pedvaxhib is indicated for routine vaccination against invasive disease caused by Haemophilius influenzae type b in infants and children two to 71 months of age. As with any vaccine, the use of Pedvaxhib may not result in a protective antibody response in all vaccines; Pedvaxhib may not induce protective antibody levels immediately following vaccination.

Comvax [Haemophilus b Conjugate (Meningococcal Protein Conjugate) and Hepatitis B (Recombinant) Vaccine] is indicated for vaccination against invasive disease caused by Haemophilus influenzae type b and against infection caused by all known subtypes of hepatitis B virus in infants six weeks to 15 months of age born to HBsAg-negative mothers.

Comvax is contraindicated in patients with hypersensitivity to yeast or any component of the vaccine. Comvax included injection-site reactions, somnolence, irritability, crying, and fever.

As with other vaccines, Comvax may not induce protective antibody levels immediately following vaccination and may not result in a protective antibody response in all individuals given the vaccine.