A randomised trial of a Haemophilus influenzae type b conjugate vaccine in a developing country for the prevention of pneumonia -: ethical considerations

In 1993 a placebo-controlled field trial of a Haemophilus influenzae type b (Hib) conjugate vaccine was started in The Gambia. At that time Hib conjugate vaccines had been shown to be efficacious in Europe and North America for the prevention of Hib meningitis. However doubts remained about their value in developing countries, where the epidemiology of Hib disease is quite different and the most important manifestation of Hib disease is pneumonia. The ethical issues facing the investigators before and during the trial are outlined in this paper, along with the views of the different groups involved in the trial. The trial demonstrated the efficacy of the vaccine in this setting and revealed the proportion of childhood pneumonia that is likely due to Hib, which was much higher than had previously been estimated. Since the completion of the trial Hib vaccines are now recommended for use in developing countries by the World Health Organization, largely based on the results of this trial. After a delay of 17 months following the completion of the trial, national Hib vaccination was started in The Gambia in 1997 using vaccine provided by a donation from industry.