We provide an additional explanation of reportedly asymptomatic MERS-CoV patients, the majority of whom were healthcare personnel in clinical settings. We were able to elicit a past background of symptoms in a majority of patients, and a substantial proportion reported the presence of symptoms as the reason for testing for MERS-CoV contamination. These findings warrant additional investigation. Our study had several limitations. Based on the epidemiology of MERS-CoV to date, the chance was considered by us of MERS-CoV transmission to be higher in health care facilities than in the community.