EARLY in March 1947, a 50 year old American business man in an early stage of smallpox came to New York from Mexico. The case was not recognized during life, and isolation was not enforced until shortly before his death. As a result, a small outbreak of smallpox occurred in March and April. There were 12 cases, with 2 deaths.1 A large number of people had been exposed, and it was considered wise to urge vaccination on all city residents. Approximately 5,000,000 people were vaccinated in about a month. This presented an opportunity to study the results of vaccination in a large group from the point of view of possible complications.
IMMUNE STATUS OF THE POPULATION
An attempt was made in the first few days to have all persons vaccinated return for a reading of the vaccination site. Unfortunately, this plan had to be abandoned on account of shortage