THURSDAY, Nov. 20, 2008 (HealthDay News) -- U.S. health officials said Thursday that a shortage of vaccine is leading them to monitor Hib infections, one of the most important causes of bacterial illness in young children.
Though the agency has yet to see an increase in cases, the stepped-up surveillance was prompted by a disruption in the supply of vaccine that has virtually eliminated Hib (Haemophilus influenzae type b) infections since it was introduced in 1988.
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 U.S. Centers for Disease Control and Prevention. Hib is not a cause of the seasonal flu.
"The shortage is not serious but it is concerning," said Michael Jackson, an epidemiologist with the CDC.
The shortfall was caused by a recall of certain lots of Hib conjugate vaccine, and then the suspension of production by drug maker Merck & Co. last December. Merck originally expected to resume production late this year, but delays have pushed that timetable back to the middle of 2009, the CDC said in its Nov. 21 Morbidity and Mortality Weekly Report.
One reason the vaccine shortage hasn't been more serious is that drug maker Sanofi-Aventis also makes Hib vaccine, Jackson said.
Before the introduction of the vaccine, some 20,000 U.S. children would get serious and sometime fatal Hib infections each year, the CDC noted.
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.
To manage the shortage, health officials are recommending giving the Hib vaccine to infants, but holding off on a recommended booster shot for children age 12 to 15 months, except those at increased risk for Hib disease.
"Right now the recommendations are to make sure all children get the primary vaccine series, and providers should defer giving the booster dose until the vaccine supply increases," Jackson said. "We are not worried about sudden increases in Hib disease, but we are worried over time that, not having the booster, we could start to see increases in Hib," he said.
The agency is asking doctors, state health departments and state laboratories to increase their surveillance of Hib.
Jackson said 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. "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 parents shouldn't panic because of the vaccine shortage.
"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.