CDC Revises Guidance on Hib and Hepatitis A Vaccination

CDC Revises Guidance on Hib and Hepatitis A Vaccination
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By Todd Neale, Staff Writer, MedPage Today
Published: September 18, 2009
Reviewed by Dori F. Zaleznik, MD; Associate Clinical Professor of Medicine, Harvard Medical School, Boston and
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Supplies of Haemophilus influenzae type b (Hib) conjugate vaccine are now sufficient for clinicians to recall children who deferred their booster dose, according to the CDC's Advisory Committee on Immunization Practices (ACIP).

If a recall isn't feasible or office vaccine supplies aren't adequate, clinicians should continue following the guidance issued in June and give booster doses during routine visits, ACIP said.

The new recommendations were published in the Sept. 18 issue of Morbidity and Mortality Weekly Report.

There was a shortage of Hib vaccine following the recall of some lots of Merck's PedvaxHIB and Comvax in December 2007.

This led ACIP to recommend deferring the booster dose -- administered at 12 to 15 months -- until supplies were replenished.

Since then, two new Hib vaccine products have been approved: Pentacel for either the primary series in infancy or the booster dose and Hiberix, which is only approved for the booster dose up to age 4.

ActHib was already on the market but production was increased earlier this summer to help address the shortage.

The recommendations released in June said the supply was sufficient to reinstitute the booster but not to recall children who had deferred getting it.

The vaccine supply is now sufficient for a recall, ACIP said in the current recommendations, and all children should get the booster as soon as possible.

In the same issue of MMWR, CDC reported new recommendations for hepatitis A vaccination for close contacts of newly arriving international adoptees from countries with high or intermediate hepatitis A endemicity.

All unvaccinated household members and other close personal contacts, such as babysitters, who come into contact with international adoptees should be vaccinated within 60 days of the adoptee's arrival, according to the recommendations.

The first dose of the two-dose series should be administered as soon as adoption is planned and ideally, at least two weeks before the arrival of the child, they stated.

The new guidance adds to previous recommendations for hepatitis A vaccination for travelers to countries with high or intermediate endemicity, as well as postexposure prophylaxis for travelers who have come into close contact with people infected with the virus.

ACIP made the current recommendations based on the likelihood that an international adoptee coming to the U.S. might be actively infected at the time of adoption.

The risk of contracting hepatitis A among close personal contacts of new international adoptees is estimated at 106 per 100,000 household contacts, the agency said.

That compares with just 1 per 100,000 contacts for the general U.S. population in 2007.

From 1998 to 2008, about 18,000 children a year were adopted from foreign countries, and of those, 99.8% came from countries where hepatitis A is of high or intermediate endemicity.

The predominant country of origin for these children has changed over time. In the early 1990s, it was South Korea. In the late '90s, most of the adoptions came from Russia and China. Currently, most come from Guatemala, China, Russia, and Ethiopia.

In these countries, according to the CDC, hepatitis A infection is highest in children younger than 5, who make up about 85% of international adoptees. In children this young, infection is likely to be asymptomatic.

The CDC has also identified cases of close contacts becoming infected by newly adopted children.

A study conducted at three adoption clinics in the U.S. found that about 1% to 6% of international adoptees are infected with hepatitis A, according to the CDC.

The ACIP members did not make any financial disclosures.

Primary source: Morbidity and Mortality Weekly Report
Source reference:
CDC "Updated recommendations from the Advisory Committee on Immunization Practices (ACIP) for use of hepatitis A vaccine in close contacts of newly arriving international adoptees" MMWR 2009; 58: 1006-07.

Additional source: Morbidity and Mortality Weekly Report
Source reference:
CDC "Licensure of a Haemophilus influenzae type b (Hib) vaccine (Hiberix) and updated recommendations for use of Hib vaccine" MMWR 2009; 58: 1008-1009.