Routine immunisation against a bacterial microorganism that can cause meningitis and pneumonia should be introduced for children in developing countries, suggests a report published in this week’s issue of The Lancet.
The study shows that disease caused by Haemophilus influenzae type b (Hib) has been virtually eliminated from children in The Gambia after the introduction of a nationwide vaccination programme.
In 1997, a trial in over 40 000 infants in The Gambia found a Hib vaccine was 95% effective against the diseases associated with Hib. However, the vaccine’s effectiveness was tested under optimum trial conditions. In routine use in developing countries, suboptimum storage and transport conditions can reduce a vaccine’s effectiveness.
Richard Adegbola (Medical Research Council, UK) and colleagues investigated the effectiveness of the Hib vaccine when delivered via The Gambia’s existing expanded programme on immunisation (EPI). Routine immunisation of infants in the Gambia with the Hib vaccine began in May 1997. The researchers monitored children in the western region of The Gambia for Hib disease from May 1997 to April 2002. A total of 5984 children were investigated as possible cases of Hib infection. When a case of the disease was confirmed a researcher recorded the vaccination status of the child. The investigators found that after the introduction of routine Hib immunisation, the annual incidence rate of meningitis in infants in The Gambia dropped sharply from over 200 per 100 000 to 21 per 100 000 in the first 2 years of vaccination. The incidence declined further to 0 per 100 000 in the fifth year after the introduction of routine immunisation. The authors note that the reduction was achieved despite difficulties with a regular supply of vaccine. No cases of Hib disease have been identified in the western region since 2002.