_To the Editor_ Norovirus is a major cause of acute gastroenteritis worldwide, and chronic infections frequently occur in immunocompromised patients. However, no US Food and Drug Administration–approved specific medication is available for treating norovirus infection. Interestingly, substantial clinical evidence has suggested that nitazoxanide, originally developed as an antiprotozoal agent, is a potential antiviral therapy for norovirus infection. Both clinical trials and case studies have reported its effects on reduction of symptom duration in immunocompetent patients or clearance of the infection in immunocompromised patients. On the contrary, a recent study in the Journal of Infectious Diseases by Kempf et al reported that nitazoxanide was not effective for treating chronic norovirus gastroenteritis in a patient with X-linked agammaglobulinemia. These results have sparked concern regarding whether this drug holds promise in treating norovirus infection, indicating the need for further assessment of the efficacy and working mechanism of nitazoxanide. [...]