Federal health officials are urging doctors and state agencies to be more careful in suspected cases of invasive Haemophilus influenzae type B (HiB) in children younger than 5, largely due to a continuing vaccine shortage that is expected to continue until the middle of 2009.
The vaccine protects against Hib disease (Haemophilus influenza type b) a bacterium estimated to be responsible for some three million serious illnesses and an estimated 386,000 deaths every year, mainly through meningitis and pneumonia.
There are varying forms of serotypes of H. influenzae, says Michael Jackson, an epidemiologist with the U.S. Centers for Disease Control and Prevention (CDC). The current vaccine helps to prevent type B, at one time the most common cause of bacterial meningitis in children.
But the reporting of serotypes to the CDC has been inconsistent with an estimated 40 percent of cases lacking such information, Dr. Jackson said.
“Without the serotype,” says Dr. Jackson, “we are unable to know if it’s type B, which is the type we are most concerned about, or another type that is less worrisome.”
The vaccine shortage began in December 2007 when Merck recalled 1.2 million doses of the vaccine. The voluntary recall began after the Merck found a bacterial contamination, Bacillus cereus on vaccine manufacturing equipment at its Pennsylvania plant.
The company has recently modified its manufacturing process, delaying vaccine availability until the middle of next year, said a spokeswoman for Merck.
While there is enough Hib vaccine to supply infants with a first series of shots, the shortage means children are going longer without the booster shots usually given after their first birthday, said CDC officials.
Agency officials encourage state and hospital laboratories, health departments and doctors to do serotyping of blood or spinal fluid specimens in a timely manner and report findings to the CDC.
The full report is published in the CDC’s weekly MMWR report on November 21, 2008.