Questions and Answers about Hib Recall

Voluntary Recall of Certain Lots of Haemophilus influenza type b (Hib) Vaccine Produced by Merck & Co., Inc.: Information for Public Health Agencies and Healthcare Providers

On December 13, Merck & Co., Inc. announced a voluntary recall of certain lots of two Haemophilus influenza type b (Hib) conjugate vaccines, PedvaxHIB® (monovalent Hib vaccine) and COMVAX® (Hib/hepatitis B vaccine). 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. Two other Hib conjugate vaccines manufactured by sanofi pasteur and currently licensed and available for use in the United States, ActHIB® (monovalent Hib vaccine) and TriHIBit® (diphtheria and tetanus toxoids and acellular pertussis [DTaP]/Hib vaccine), are unaffected by the recall. However, sanofi pasteur likely will not be able to immediately provide adequate Hib vaccine to vaccinate fully all children for whom the vaccine is recommended.

The recommended vaccination schedule for all available Hib-containing vaccines consists of a primary series (consisting of 2 or 3 doses, depending on the formulation) administered beginning at age 2 months and a booster dose at age 12–15 months. Because of the short-term reduction in available doses of Hib-containing vaccines, CDC recommends that providers temporarily defer administering the routine Hib vaccine booster dose given at age 12–15 months except for children in specific groups at higher risk.

CDC is also asking providers to order only the number of doses of vaccine required to meet immediate needs (i.e., a supply for up to 4 weeks) and to refrain from attempting to build an inventory of Hib vaccine.

Consult the CDC’s interim recommendations for the use of Hib conjugate vaccines.

Questions
What vaccine is being recalled?
Merck & Co. has initiated a voluntary recall in the United States for ten lots of PedvaxHIB® [Haemophilus b Conjugate Vaccine (Meningococcal Protein Conjugate)] and two lots of COMVAX® [Haemophilus b Conjugate (Meningococcal Protein Conjugate) and Hepatitis B (Recombinant) Vaccine]. The affected doses were distributed in the U.S. starting in April 2007.

The lots that are being recalled are:

Product Description
Lot #
Expiration Date
PedvaxHIB® 0677U 11 January 2010
PedvaxHIB® 0820U 12 January 2010
PedvaxHIB® 0995U 16 January 2010
PedvaxHIB® 1164U 18 January 2010
PedvaxHIB® 0259U 17 October 2009
PedvaxHIB® 0435U 18 October 2009
PedvaxHIB® 0436U 19 October 2009
PedvaxHIB® 0437U 19 October 2009
PedvaxHIB® 0819U 09 January 2010
PedvaxHIB® 1167U 10 January 2010
COMVAX® 0376U 05 January 2010
COMVAX® 0377U 08 January 2010
Another lot of PedvaxHIB® was also recalled, but it was only used in China. No other U.S. lots of PedvaxHIB® or COMVAX® and no other Merck products are affected by this recall.

Why are these lots being recalled?
Merck is taking this step as a precautionary measure. The company cannot assure sterility for these specific vaccine lots. The potential contamination in these specific lots was identified as part of Merck’s standard evaluation of their manufacturing processes. In routine testing of the vaccine manufacturing equipment used to produce PedvaxHIB® and COMVAX®, Merck identified the presence of a bacteria called Bacillus cereus. Sterility tests of the vaccine lots themselves prior to their release have not found any contamination.

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

What is the extent of the recall?
About 1 million doses of vaccine are being recalled, including ten lots of PedvaxHIB® and two lots of COMVAX® that were distributed in the U.S. as well as vaccine lots within the CDC stockpile.

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 efficacy have been identified for these vaccine lots.

What are the risks to children who received vaccine from affected lots?
Sterility tests of the vaccine lots themselves have not found any contamination. Merck has not received any reports of abscesses or disseminated B. cereus infection in children who received vaccines from affected lots. However, since sterility of the vaccine cannot be assured, there may be a risk of developing localized or disseminated infections. Immunocompromised children may be at the greater risk for these infections. These infections are most likely to occur within one week after vaccination.

The Vaccine Adverse Event Reporting System (VAERS) will continue to monitor adverse events following vaccination as they are reported. Any potentially vaccine-related adverse events should be reported to VAERS at 1-800-822-7967 (or at http://www.vaers.hhs.gov). With any public attention that a vaccine receives, it is expected that VAERS will see an increase in the number of adverse events reported to the system. These reports help CDC and FDA determine if the reported events may have been caused by the vaccine. While VAERS has received some reports involving the recalled lots of Hib vaccine, there is no evidence of adverse events related to bacterial contamination of these lots.

What should providers do if they have recalled lots in their office?
Providers should immediately discontinue use of any of the affected lots and follow Merck’s instructions for returning recalled vaccine (both VFC and non-VFC vaccine).

How does this impact the nation’s Hib vaccine supply? Are there other Hib vaccine manufacturers?
As a result of this recall, providers who only use Merck Hib vaccines may have none, some or all of their vaccine recalled, and about half of the Hib vaccine in CDC’s stockpile was recalled. There are two U.S. Hib vaccine manufacturers – Merck & Co., Inc. and sanofi pasteur. In the past, each manufacturer has produced about half of the nation’s Hib vaccine supply. 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. Sanofi pasteur likely will not be able to immediately provide adequate Hib vaccine to vaccinate fully all children for whom the vaccine is recommended.

What is CDC doing in response to the shortage of Hib vaccine?
CDC, in consultation with the Advisory Committee on Immunization Practices (ACIP), the American Academy of Family Physicians, and the American Academy of Pediatrics, is recommending that providers temporarily defer administering the routine Hib vaccine booster dose given at age 12–15 months except to children in specific groups at high risk. CDC will continue to monitor the supply of available Hib vaccines and work closely with the vaccine manufacturers to equitably distribute vaccine to meet immediate needs.

Will the shortage of Hib vaccine result in an increase in disease occurrence of Haemophilus influenza type b?
Fortunately, current immunization rates in the U.S. for Hib vaccine are high. In 2006, about 94% of U.S. children 19-35 months of age were vaccinated against Hib. This has resulted in a dramatic decline in transmission of this bacteria; however, it has not gone away completely. Experience has shown that we cannot let down our guard against vaccine-preventable diseases such as Hib. When immunization rates fall we are susceptible to increases in disease occurrence, so we are taking the current situation very seriously.

What should providers tell their patients?
If concerned parents contact their providers, they should be informed that children who were vaccinated with vaccine affected by this recall do not need to be revaccinated. Although there is no evidence of adverse events related to bacterial contamination of these lots, parents of children recently vaccinated with recalled vaccine should watch for any signs of infection (such as marked redness and swelling at the injection site) and contact their providers if such reactions occur. It should be emphasized that sterility tests of samples from the recalled lots have not found any contamination and the potential of contamination of any individual dose of Hib vaccine is very low.

What should providers do if they have no vaccine or little vaccine in their office?
Providers who are completely out of Hib vaccine can contact sanofi pasteur regarding the availability of Hib vaccine to meet immediate short term needs. To maximize the amount of available vaccine, providers should order only the number of doses of vaccine required to meet immediate needs (i.e., a supply for up to 4 weeks) and should refrain from attempting to build an inventory of Hib vaccine. VFC providers should contact their health department.

Are some children at high risk for Hib?
Yes. Children at increased risk for Hib include: children with sickle cell disease, leukemia and malignant neoplasms, HIV and certain other immunocompromising conditions, asplenia, as well as American Indian and Alaska Native children. Vaccinating these children according to the recommended schedule is a high priority. Additional information for providers who serve American Indian and Alaska Native children can be found in CDC’s interim recommendations.

What safety monitoring is underway for affected Hib vaccines?
CDC is monitoring the safety of the affected Hib vaccine lots by reviewing adverse event reports received by the Vaccine Adverse Event Reporting System (VAERS). VAERS is a national passive reporting system that accepts and monitors reports of adverse events following vaccination. Any potentially vaccine-related adverse events should be reported to the Vaccine Adverse Event Reporting System (VAERS) at 1-800-822-7967 (or at http://www.vaers.hhs.gov).

In addition, CDC is working with state health departments to identify any cases of B. cereus infections in vaccinated children. Clinicians who identify a patient aged younger than 6 years meeting the following criteria should contact their state health department:

if the child had isolation of B. cereus from a specimen other than feces or vomitus after any vaccination, and
if the child was immunized with any vaccine after March 31, 2007.
Note: Merck has a National Service Center that can answer questions about medical and other issues related to this recall, 1-800-672-6372.

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