Can We Eliminate Haemophilus Influenzae Type B?

Modern medicine can boast about eliminating diseases through immunizations. The greatest success story was the eradication of smallpox form the face of the earth in the late 1970s. Then, when polio was eliminated from the Western Hemisphere, the World Health Organization (WHO) embarked on a mission to eliminate it from the rest of the world. Unfortunately, this goal has not been achieved yet.

Public health experts think that after polio is eliminated, the next target could be measles. Meanwhile, routine immunization has put under control many devastating diseases of the past. One example is the disease caused by the bacterium Haemophilus influenzae type b (Hib), which infects the outer lining of the brain causing meningitis.

Invasive Hib disease is most common among children under five years of age and can lead to pneumonia, severe throat swelling and infections of blood, bones, joints, and the covering of the heart. Even with antibiotic treatment, about 5% of children (500 out of every 10,000) with Hib meningitis die. Hib kills 400,000 children in the world every year.

The first Hib vaccine was licensed in 1985. Before then, there were 20,000 cases of Hib disease every year in the United States (including 12,000 cases of meningitis and 7,500 cases of pneumonia). The number of cases began to drop dramatically after the introduction of the vaccine: only 34 cases were reported in 2002.

Consider the impact of the Hib vaccine in other countries:

•United Kingdom, 87% decrease in the number of cases
•Chile, 90% decrease
•The Gambia, 100% decrease

A new study published in the August 9 issue of the Journal of the American Medical Association (JAMA) shows a similar impact in Kenya.*

Hib routine immunization was introduced in Kenya in 2001. This was possible through the financial support of the Global Alliance for Vaccines and Immunization (GAVI). To be eligible for GAVI's support, the country's per capita gross domestic product should be less than $1,000. Currently, GAVI supports 11 African nations.

The JAMA study compared the number of new cases of invasive Hib disease in hospitalized children in the 2 years before and the 4 years after introduction of the Hib vaccine.

The researchers found that after three years of routine vaccination against Hib, the disease rates fell 88%. According to the study, the vaccine prevented an estimated 3,370 hospitalizations in 2005.

After the study was published, a GAVI statement said that routine use of the Hib vaccine could lead to the virtual elimination of this disease in Africa.

Unfortunately, according to GAVI, less than 40% of African countries have adopted the Hib vaccine. "One major obstacle has been the lack of available data on Hib disease burden and vaccine effectiveness," the alliance said.

The new data from Kenya should convince other countries of the effectiveness of the vaccine and the positive impact of immunizing children against Hib. Perhaps one day the world can be rid of this terrible disease.

* Effectiveness of Haemophilus influenzae Type b Conjugate Vaccine Introduction Into Routine Childhood Immunization in Kenya. KD Cowgill, M Ndiritu, J Nyiro, et. al. JAMA, 2006;296:671-678.