Information for Parents on the Recall of Merck Haemophilus influenzae type b (Hib) Vaccine
What vaccine is being recalled?
Certain lots of the Haemophilus influenzae type b (Hib) vaccine are being recalled. The vaccines are manufactured by Merck & Co. and the brand names of the vaccines are PedvaxHIB® vaccine and COMVAX® (COMVAX® is a combination vaccine containing Hib and hepatitis B vaccine). Ten lots of PedvaxHIB® vaccine and two lots of COMVAX® vaccine are being recalled. Lots are batches of vaccine that are identified by a number on each vial of the vaccine.
What is Hib disease?
Hib disease is a cause of severe bacterial infections in young children. It usually affects children under the age of 5. Hib meningitis (infection in the covering around the brain) can result in death or permanent brain damage. The occurrence of Hib disease has diminished by more than 99% since the vaccine was introduced.
Why are these lots being recalled?
During regular testing of the vaccine manufacturing equipment used to produce PedvaxHIB® and COMVAX®, Merck found a certain bacteria called Bacillus cereus. Tests of the vaccine lots themselves have not found any contamination. However, Merck is voluntarily taking this step as a precautionary measure.
Will children who received vaccine from affected lots need to be revaccinated?
No. Children who received Hib vaccine from affected lots do not need to be revaccinated. No concerns about how well these vaccines work have been identified for these vaccine lots.
What are the risks to children who received vaccine from affected lots?
Tests of the vaccine lots themselves have not found any contamination. In addition, no problems have been detected by the Vaccine Adverse Event Reporting System (VAERS) or by the manufacturer related to the Hib vaccine affected by this recall. If a child was vaccinated with a vial of PedvaxHIB® or COMVAX® that contained B. cereus or other bacteria, there may be a risk of developing an infection, especially at the spot where the vaccination was given. Children who have problems with their immune systems may be at greater risk for these infections. These infections would most likely occur within one week after vaccination.
What should parents do if their child was vaccinated with one of the recalled lots?
Parents do not have to have their child revaccinated. The vaccine that their child received will provide good protection against Hib disease. It should be emphasized that none of the recalled vaccine has been found to be contaminated with bacteria, so the likelihood that any adverse reactions will occur is extremely low. But any bacterial infection that might occur from contaminated vaccine would be expected within a few days of the immunization. Parents should discuss any concerns they have with their doctor.
Will there be a shortage of Hib vaccine because of the recall?
During the next few months it is anticipated that there will be less Hib vaccine available than normal. However, doctors are being advised on how to make the best use of their Hib vaccine. Doctors should be able to provide the primary series of 3 vaccinations for all children, but will likely defer the booster dose, usually given at age 12-15 months, in low-risk children. Deferral of the booster dose will be short-term and is not likely to result in increased risk for Hib disease. Deferral will continue until the supply of Hib vaccine increases, probably by the end of 2008.