RECENTLY there has been a trend toward starting inoculations against diphtheria and whooping cough at an age earlier than 6 to 7 months. In reply to a questionnaire which was answered by 9 of 12 Medical Officers of Health of various cities in Canada, 6 indicated that they were recommending immunization against these two diseases starting at 3 to 4 months of age. Neither Montreal nor Toronto, Canada's two largest cities, endorse this view at the moment.
One of the principal objectives of any immunization program is the reduction of mortality. Before any change in a program should be considered therefore, one must ask at least two questions. First of all, is the program that is now in use satisfactory? That is, is there really any necessity for changing it? Second, will the recommended change make any difference in mortality figures?
Table 1 shows the total number of deaths from