In September 1935, Dr Michael O'Farrell, Waterford CMO, put forward a proposal to introduce anti-diphtheria immunization in the county. The board of health sanctioned the scheme, and ordered 144 25 c.c. bottles of TAF antigen from Burroughs Wellcome, Beckenham, Kent, through the Dublin based medical suppliers, Fannin & Company. Over the course of twelve months, 1,070 children received 3,378 injections of TAF without incident. In September 1936, following representations by the local government department, O'Farrell encouraged school principals in Dungarvan to implement anti-diphtheria immunization schemes. The administrators of St Augustine's Friary School in Dungarvan and Ring College, a private boarding school located outside the town, secured parental permission to have their students treated and authorized Dr Daniel McCarthy to proceed with inoculations at both schools. McCarthy secured ten bottles of Wellcome's toxin TAF antigen from O'Farrell's local government stock, and commenced immunization at St Augustine's and at Ring College.

McCarthy visited St Augustine's over the course of three days in November 1936, where he treated 44 children with parental consent. On three separate days, McCarthy treated 38 children, including two of his own, at Ring College. Each child received three 1 c.c shots at weekly intervals, and following standard ‘three-shot’ procedure, children received the first and third injections in the right arm, and the second injection in the left arm. No complications ensued and in due course, the children returned home for the Christmas holidays.

In early January 1937, McCarthy received a visit from Bríd Bean Uí Cionnfaola, mother of Siobhán O'Cionnfaola, a 12-year-old girl who received immunization treatment at Ring College, stating that her daughter was suffering from a sore arm, which developed during the Christmas holidays. On examination, McCarthy found Siobhán to be in poor health, anaemic, and debilitated. Furthermore, the girl's axillary glands were enlarged and tender, and a small discharging ulcer had developed on her right arm, where she received the intramuscular injection. McCarthy advised Bean Uí Cionnfaola regarding treatment of the local condition and prescribed for her daughter's general health.

In early February 1937, Jack Saunders, Cork city's chief medical officer, learned that two children were under private medical care in Cork city following immunization treatment at Ring College. Both children complained of sore arms during the Christmas holidays, but the matter escaped close attention until Christmas Day when their mother, Mrs Cussen, became alarmed and summoned a doctor.