THURSDAY, June 25, 2009 (HealthDay News) -- A children's vaccine that's been in short supply for 18 months is now being produced at levels that allow its traditional widespread use, officials at the U.S. Centers for Disease Control and Prevention announced Thursday.
Beginning in December 2007, the agency recommended that parents forego booster shots for Haemophilus influenzae type B (Hib), an infection that can lead to bacterial meningitis. A booster shot of the vaccine was traditionally recommended for children at ages 12-15 months, but that was curtailed following a shortfall in supply from one of the two manufacturers of the vaccine, Merck & Co.
At the time, the CDC said the shortage meant that shots should be restricted to the initial series given to infants at 2, 4 and 6 months of age.
But as reported in the June 25 issue of the CDC journal Morbidity & Mortality Weekly Report, "the supply of Hib-containing vaccine is now sufficient to reinstate the on-time booster dose administration of Hib vaccine at 12-15 months for all children who completed the primary series."
While Merck continues to suspend its production of the Hib vaccine, another company, Sanofi Pasteur, plans to boost production of its two Hib vaccines, starting in July, to meet the demand, the CDC said.
However, supplies are still somewhat limited, and the CDC does not recommend that children who missed the booster shot during the past 18 months rush out now to get the vaccine. "Although supply is sufficient to reinstate the booster dose, there is currently only enough supply for limited catchup," the CDC noted. Parents of children who missed the booster shot at 12 to 15 months should wait until their "next routinely scheduled visit or medical encounter" and discuss the situation and their particular child's need for the shot with their doctor, the CDC said.
The CDC also noted that many children may have received Hib immunization through certain combination vaccines such as the DTaP-IPV/Hib (Pentacel), so physicians need to assess this carefully "to ensure appropriate coverage while minimizing extra doses of unneeded vaccine."
Last November, CDC officials said the Hib vaccine shortfall had caused them to monitor Hib infections. At the time, the agency said it had not yet seen any increase in cases. However, it said that stepped-up surveillance was important since the vaccine had virtually eliminated Hib infections in the United States since its introduction in 1988. Before the introduction of the vaccine, some 20,000 U.S. children would get serious and sometime fatal Hib infections each year, the CDC said.
Hib infection can cause a variety of illnesses, including meningitis (inflammation of the membranes covering the spinal column and brain), blood stream infections and pneumonia, according to the CDC. Hib is not a cause of the seasonal flu.
"The shortage is not serious but it is concerning," Michael Jackson, an epidemiologist with the CDC, said in November.
The shortfall was caused by Merck's recall of certain lots of Hib conjugate vaccine, followed by a suspension of production beginning in December 2007. At the time, Merck spokeswoman Amy Rose said that problems with the vaccine's sterilization process necessitated recalling the vaccine and then stopping production. The vaccines are marketed as PedvaxHIB and Comvax.
The fact that Sanofi-Pasteur makes the Hib vaccine rendered the shortfall less severe, Jackson said.
He noted that tracking Hib cases isn't easy. There are many different types of influenzae and there are many steps involved in testing and reporting the various types, so information often gets lost along the way, he said.
"The information we are getting at CDC is that we are missing about 40 percent of cases," Jackson said in November. "That's a little worrisome because that's 40 percent of people we don't know if they have type b, which is the vaccine-preventable one, the one we are really worried about, or if they have something else. It makes it harder for us to see changes in Hib if there really is something going on in the population."
Dr. Marc Siegel, an associate professor of medicine at New York University School of Medicine, said at the time that parents whose children missed the booster shot shouldn't panic.
"There used to be 20,000 cases a year, but the vaccine has brought it to less than 100," Siegel said. "The numbers remain small. We've almost stamped this thing out with the vaccine, so don't assume your kid is going to get it."
For more on Hib disease, visit the CDC.