The Child Welfare Association of Montreal began active immunization against diphtheria of children attending its health centers throughout the city in May 1926, and this work has been carried on as an integral part of its health program since then. This study covers the period from May 1926 until the end of 1934.
At first, groups of children over 1 year old were inoculated at a number of health centers just as soon as a convenient number of cards were signed by parents signifying their desire to have their children treated, after the nurses had explained the advisability and urgency of having this done. As a result of the launching of this campaign against diphtheria, over 1,200 children were given injections during the first year. During the following year, immunization against diphtheria was introduced in every health center, and diphtheria toxoid was administered to each child when he or she