Measles Vaccine Reactions in a Virgin Population1

Indians of an Amazon tribe, virgin with respect to measles, have been vaccinated with the Schwartz strain of attenuated measles virus. The average of the maximum observed temperatures during the period of vaccine reaction was higher in the Indians than in control groups, but no serious complications were encountered. An epidemic of the common cold, concurrent with the first of the vaccinations, may have influenced reaction rates in some vaccinees. Other factors that may have affected the reactions are discussed and consideration is given to possible parallels between the vaccine reactions and wild measles in primitive populations.