March 27, 1991

Risk Factors for Measles in a Vaccinated Population

Author Affiliations

Linda Cook University of Pennsylvania Philadelphia

Linda Cook University of Pennsylvania Philadelphia

JAMA. 1991;265(12):1527. doi:10.1001/jama.1991.03460120041021

To the Editor.—  In the recent article by Mast et al,1 the age distributions of cases and controls were different. The control group was generally younger (38% were younger than 9 years) than the study group (7% were younger than 9 years). The age disparity may cause a few problems.We cannot assume that the attack rates are similar for all ages. Davis et al2 found the age-specific attack rate to be 13% in children younger than 16 months, 2.9% in children between 5 and 9 years of age, and 0.5% in children between 15 and 19 years of age. It is therefore possible that the relatively older study group had a different type of social contact than the control group. Preschoolers' type of playing certainly enhances salivary and respiratory exchange and, therefore, risk of acquiring the measles virus. Moreover, in the absence of an age-matched control group,