CDC scientists find children given the MMR vaccine shed the measles virus for at least 2 weeks after getting the vaccine, making them vectors to spread measles.
Detection of Measles Virus RNA in Urine Specimens from Vaccine Recipients
Paul A. Rota, Ali S. Khan, Edison Durigon, Thomas Yuron, and William Bellini. Journal of Clinical Microbiology, Vol. 33, No. 9, Sept. 1995, p. 2485–2488.
“For the study, daily urine samples were obtained from either 15- month-old children or young adults following measles immunization. Overall, measles virus RNA was detected in 10 of 12 children during the 2-week sampling period. In some cases, measles virus RNA was detected as early as 1 day or as late as 14 days after vaccination. Measles virus RNA was also detected in the urine samples from all four of the young adults between 1 and 13 days after vaccination. This assay will enable continued studies of the shedding and transmission of measles virus and, it is hoped, will provide a rapid means to identify measles infection, especially in mild or asymptomatic cases.”