The reappearance of the childhood infectious disease Haemophilus influenza type B (Hib) in Minnesota last year has prompted authorities to acquire extra vaccines. The Minnesota Department of Health is urging parents to work with their health care providers so that infants receive the recommended primary series of three doses of Hib vaccine.

Of the five cases reported in the state in 2008, three were among unimmunized children, while another infected a child was too young to complete the primary series. The fifth child had received the primary series, but had an underlying problem which was later detected.

Dr. Ruth Lynfield, state epidemiologist, said “We have not seen this number of cases in young children since 1992. It is extremely sad to see this disease resurface, resulting in very severe illness including meningitis and death. These cases underscore the importance of maintaining high vaccination rates.”

Hib is a bacterial infection, usually a severe one, that typically infects infants, but can also infect young children. Most Hib patients have to be hospitalized. The patient can suffer serious complications, such as meningitis, bloodstream infection, severe swelling of the tissue of the throat resulting in breathing difficulty (epiglottitis), pneumonia, and bone/joint infections.

The Minnesota Department of Health informs that there has been a Hib vaccine national shortage since November 2007. The shortage is expected to last until the middle of this year. In order to cope with the current shortage, national advisory groups advise health care providers to defer giving a fourth and final booster Hib jab to children aged 12-15 months so that as many babies as possible complete the primary series. However, Minnesota Department of Health officials say that the shortage has also resulted in fewer babies receiving the primary series.

The plan to defer the booster dose to make sure more babies get the primary vaccinations has worked in other US states, but not in Minnesota. This could be because a greater percentage of Minnesota health care providers have traditionally used the Merck vaccine, which is in shortest supply.

Kristen Ehresmann, immunizations program manager for the Minnesota Department of Health (MDH), said “Recent data on Minnesota’s immunization rates during the Hib vaccine shortage show that fewer infants are getting a third dose than we would normally expect. As many as 18 percent fewer infants at seven months were getting the third dose of Hib compared with the two other vaccines given at age 6 months. The decrease in the level of Hib immunization results in a drop in “herd immunity”, where unimmunized and under-immunized children are vulnerable to Hib disease.”

MDH says it is working with the Centers for Disease Control and Prevention (CDC) and Sanofi-Pasteur, a vaccine manufacturer, to make an additional 37,000 Hib vaccines available over the next few months.

Ehresmann added “Since we are seeing a resurgence of Hib disease, it’s important for parents of infants to work with their health care provider or clinic to make sure their baby has received three doses of Hib vaccine. If your child hasn’t received all three Hib shots, schedule additional visits as soon as possible. Some parents have read information that encourages them to refuse or delay vaccinations for their child. However, this puts their children and other children at risk for serious diseases, such as Hib,” Ehresmann said.

Hib vaccine became available for use in babies in 1991. Before the vaccine, 20,000 cases of Hib occurred every year in the U.S., mostly among children under five years old. After the widespread use of vaccine, Minnesota rarely recorded more than 1 or 2 cases of Hib a year, often none.

Before vaccine was available, Hib accounted for 50-60 percent of all cases of meningitis in the U.S. Of these, 2-5 percent died and 15-30 percent experienced lasting brain damage or deafness.

Parents who have questions about their child’s vaccination status should talk to their health care provider. More information on Haemophilus influenzae type-b and the vaccine can be found on the MDH Website.

Written by – Christian Nordqvist