1723. Mumps Attack Rates Following Administration of a Third Dose of MMR Vaccine to School-Aged Children, Arkansas, 2016–2017

During the 2016–2017 school year, the largest mumps outbreak in the United States since 2006 occurred in Arkansas with nearly 3,000 cases. As part of outbreak response, a third dose of measles–mumps–rubella vaccine (MMR3) was offered at 27 schools with mumps attack rates ≥5 cases/1,000 students. We compared attack rates after vaccination clinics among students who received MMR3 and students with 2 MMR vaccine doses