Environmental tobacco exposure is associated with vaccine modified measles in junior high school students

Vaccine modified measles (VMM) affects individuals with attenuated vaccine induced immunity. An outbreak of measles occurred in a junior high school, starting from an unvaccinated eighth-grade student who developed natural measles and affected a majority of students who were immunized with a low potent strain of measles vaccine (TD97). To determine whether environmental tobacco smoke (ETS) exposure was associated with the development of VMM in this population, a questionnaire was used asking whether students had VMM symptoms during the outbreak and the smoking status of family members. VMM was defined in the study population as occurrence of fever and/or erythema, along with documented history of measles vaccination. A total of 513 students (85.9%) responded. Overall, the presence of in-house smokers did not differ between VMM students (49.3%) and non-VMM students (50.2%). However, in the ninth grade, presence of an in-house smoker was significantly higher in the family of VMM students (54.0%) than in non-VMM students (36.6%) (P = 0.044). Urinary cotinine levels were also measured in selected students (n = 37). Among families with at least one smoker, urinary cotinine levels were significantly higher in VMM students than in non-VMM students (P = 0.032). Furthermore, a multivariable logistic regression analysis showed that a high urinary cotinine level (>10 ng/mg creatinine; 13.5 percentile) was associated with the development of VMM. Our findings suggest that a high level of ETS exposure may be associated with an increased risk of VMM in a population with attenuated vaccine induced immunity against measles.