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ATLANTA -- Physicians should resume giving booster vaccinations for Haemophilus influenzae type b to children aged 12-15 months at routine visits, the Centers for Disease Control and Prevention recommended.
H. influenzae type b (Hib) vaccine supplies were severely reduced almost 2 years ago when Merck & Co. voluntarily recalled certain lots of its PedvaxHIB (monovalent Hib vaccine) and Comvax (Hib-HepB) vaccines; production of those vaccines has not resumed. Because of the resulting vaccine shortage, the CDC recommended at that time (December 2007) that physicians defer the 12- to 15-month Hib booster in healthy children (MMWR 2009;24:673-4).
Beginning July 1, 2009, Sanofi Pasteur, manufacturer of ActHIB (monovalent Hib vaccine) and Pentacel (DTaP-IPV/Hib vaccine), will ramp up production of those vaccines, allowing enough supply to resume the 12- to 15-month booster dose, Dr. Abigail Shefer said at a meeting of the CDC's Advisory Committee on Immunization Practices.
However, vaccine supply still will be insufficient to support a mass notification process in which all children whose booster dose was deferred would be contacted. Instead, physicians should review records and administer any needed doses during routine visits and other medical encounters, said Dr. Shefer of the CDC's immunization services division, National Center for Immunization and Respiratory Diseases.
Whenever possible, providers should match the type of booster dose (monovalent or combination) to what the child received in the primary series. However, the child still should be vaccinated if the only available vaccine does not match the vaccine type received in the primary series.
Both public and private providers will be able to order some additional doses of Hib vaccine each month, with allotments based on previous purchasing patterns or the size of the practice's birth cohort and estimates of additional needs. "Practices need to develop a tailored plan that best suits their office environment," Dr. Shefer said.
For example, practices using Pentacel for Hib need to ensure that they have adequate supplies of monovalent hepatitis B vaccine, which also is in short supply, she noted.
Fortunately, the Hib vaccine shortage does not appear to have resulted in an increase in the number of disease cases in children less than 5 years of age, said the CDC's Dr. Michael L. Jackson. Between May 2008 and April 2009, a total of 43 cases were identified, compared with an annual average of 31.4 cases prior to the shortage. The difference was not statistically significant.
Moreover, 32 states reported several Hib cases at or below baseline and just 20 states were over baseline, but none significantly. No differences were seen in characteristics of the Hib cases during the shortage compared with prior cases in either the mean age (10.9 months during the shortage vs. 13.7 months before the shortage) or percentage of unvaccinated cases or undervaccinated cases (66% vs. 54%), said Dr. Jackson of the CDC's meningitis and vaccine preventable diseases branch.
And there is more good news: Another Hib vaccine, GlaxoSmithKline's Hiberix, is waiting in the wings to enhance the booster supply. The company submitted a biologic license application for Hiberix with the proposed indication as a booster dose at 15 months to less than 5 years of age for the prevention of invasive disease. Data submitted to the Food and Drug Administration come from seven studies (including six that assess immunogenicity) with "core" data involving a total of 1,008 subjects, and two studies with a total of 1,396 subjects providing "supportive" data, GSK's Dr. Remon Abu-Elyazeed said at the meeting.
Those studies demonstrate that a booster dose of Hiberix provides strong immune responses in children who were previously primed with Hib vaccine, and is immunogenic when coadministered with other common pediatric vaccines, said Dr. Abu-Elyazeed, head of GSK's pediatric vaccines division.
Hiberix is already on the market in 98 countries, with a distribution of more than 54.9 million doses.
As to when it will be available in the United States, Dr. Norman Baylor of the FDA said, "Our goal is to get this done as soon as we can."
Denise Fulton contributed to this report.
For more information on the Hib vaccine shortage, visit the Web site www.cdc.gov/ vaccines/vac-gen/shortages/default.htm. For the routine Hib schedule, go to www.cdc.govvaccines/recs/schedules/ default.htm#child.
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