Health

Advisory

IMPORTANT CDC HIB VACCINE INFORMATION

POSTED: MARCH 19, 2009

The following information is from the Centers for Disease Control and Prevention as distributed on March 18, 2009.

Invasive Haemophilus influenzae Type B Disease in Young Children and Importance for All Young Children to Receive 3 Dose Primary Series

with Available Hib-containing Vaccine

Background of the Hib Vaccine Shortage

Health care providers must be vigilant about ensuring that all young children are appropriately vaccinated with the 3 dose primary series

of Hib (Haemophilus influenzae type b ) vaccine. A nationwide shortage of Hib vaccine began in December 2007 and is ongoing. The

recall of certain lots of the two Hib-containing vaccines produced by Merck & Co., Inc. and cessation of production of both vaccines

has left only one manufacturer of Hib vaccine in the United States (Sanofi Pasteur). The shortage resulted in a recommendation by CDC to

defer the Hib booster (routinely recommended at 12 through 15 months) for children who are NOT at high risk of Hib infection temporarily,

until supplies are restored. This recommendation is still in effect.

Temporary deferral of the booster dose at 12 through 15 months of age for non-high risk children may have resulted in increased Hib

carriage and transmission in non-symptomatic children. There is potential to see increases in cases of Hib disease at the local level.

During 2008 in Minnesota, five children aged 5 months through 3 years were reported with invasive Hib disease; one died. Three patients

had received no vaccinations because of parent or guardian deferral or refusal. One child was aged 5 months and had received 2 doses of

Hib PRP-TT vaccine in accordance with the primary series schedule. Another child had received 2 doses of Hib PRP-OMP vaccine, but no

booster dose, per CDC recommendations during the shortage. Subsequent to Hib infection, this child was diagnosed with

hypo-gammaglobulinemia. The five cases in 2008 were the most reported for 1 year from Minnesota since 1992, when 10 cases were reported.

There is enough Hib-containing vaccine for all U.S. children to receive the primary series. All children should complete the primary

series by 7 months of age; high risk children should continue to receive the full primary series and the booster dose.

Completion of the primary series with currently available vaccine products (manufactured by Sanofi Pasteur) requires a total of 3 doses

of Hib-containing vaccine (2, 4, and 6 months). Although there is enough Hib-containing vaccine nationally to support these

recommendations, there may be times when practitioners do not have an adequate supply of vaccine to meet local demand. If Hib vaccine is

not available in the office at the time of a visit, children who are unable to receive one of the primary series doses should be tracked

and recalled to schedule an appointment to receive their dose as soon as vaccine becomes available in the office.

In addition, using available Hib-containing vaccines has presented challenges associated with switching from the Merck to Sanofi products

for some providers.

There are indications that these challenges have led to lower completion of the primary series. Preliminary information comes from

sentinel immunization information systems (registries) in select states, which have indicated up to 10% lower coverage with the third Hib

dose in the primary series compared to other vaccines (DTaP, PCV7) commonly administered at the same visit. In the scenario of booster

dose deferral, it is even more important that all infants receive the complete primary series.

Specifically, some of the challenges in using the currently available Hib-containing vaccines have included provider reluctance to switch

inventory and schedules, misunderstanding regarding what constitutes primary versus booster doses, determining a catch-up schedule in the

setting of the deferred booster, and provider and parent concerns about over vaccination resulting from switching to the Sanofi Pasteur

Hib-containing vaccine. Despite these challenges, health care providers need to ensure that all children are appropriately vaccinated

with the primary series. For example, if Pentacel (DTaP-IPV/Hib) is the only Hib-containing vaccine available, this combination product

should be used to complete the primary series, even if doing so results in receipt of additional doses of other antigens (e.g., DTaP,

IPV). The Hib-containing vaccine products that are available may not be what providers used previously in their practice; however, the

potential for increased transmission of Hib makes it more important than ever that every child is adequately protected.

Recommendations

The following non-high risk children should be scheduled to receive the primary series of Hib vaccine as outlined below:

• If the child is at least 6 weeks but less than 12 months of age and has received zero, one, or two doses of Hib vaccine, schedulehim/her for the first or next dose(s) immediately with a minimum of four weeks between the doses. These children will need one booster

  dose when the Hib vaccine shortage is over.

• If the child is between 12 and 14 months of age and has not had any doses of Hib vaccine, schedule appointments for two doses, eightweeks apart.
• If the child is between 12 and 14 months of age and has received Hib vaccine but did not complete the primary series before theyturned 1 year old (i.e., had 1 dose of the Merck product OR 1-2 doses of the Sanofi product), schedule an appointment for 1 additional

  dose, a minimum of eight weeks from the last dose.

• If the child is at least 15 months of age but less than 5 years of age and has not received any doses of Hib vaccine OR has notcompleted the primary series (i.e., had 1 dose of the Merck product OR 1-2 doses of the Sanofi product), schedule an appointment for one

  dose.

• If the child is 5 years old or older and hasn’t received any Hib vaccine, Hib vaccine is not necessary.

Certain children are at increased risk for Hib disease, including children with asplenia, sickle cell disease, human immunodeficiency

virus infection and certain other immunodeficiency syndromes, and malignant neoplasms. CDC recommends that providers continue to

vaccinate these children with available Hib conjugate vaccines according to the routinely recommended schedules, including the 12 through

15 month booster dose. Providers who serve predominantly American Indian/Alaska Native (AI/AN) children living in AI/AN communities

should continue to stock and use PRP-OMP– containing Hib vaccines (Merck product) and vaccinate according to the routinely

recommended schedule, which includes the 2-dose primary series (ages 2 and 4 months) and a 12 through 15 month booster dose. This product

is available from the VFC Pediatric Vaccine Stockpile, through their state immunization programs.

For more information about Hib disease and vaccination please call the Delaware Immunization Program Hotline at 1-800-282-8672 or the CDC

at 1-800-232-4636/1-800-CDC-INFO or by email at www.cdc.gov/vaccines/about/contact/nipinfo_contact_form.htm.