Table 1.

Classification of cases and case definitions

Case classification	Case definition
Confirmed case	A patient with no known positive HCV test result before the date of implicated surgical procedure at facility A or B, a positive HCV test result ≥2 weeks after the surgical procedure, and genotype 1b HCV infection, with HCV viral sequences highly related to those of the HCV-infected surgical technician
Possible case	A patient with no known diagnosis of HCV infection before the date of implicated surgical procedure at facility A or B, a positive HCV test result ≥2 weeks after the surgical procedure, and HCV genotyping and/or HCV viral sequencing could not be performed
HCV-infected–not related to surgical technician	A patient with a diagnosis of HCV infection before the date of surgical procedure at facility A or B, or HCV infection with a genotype not 1b, or genotype 1b HCV infection, with HCV viral sequences not highly related to those of the HCV-infected surgical technician
HCV-negative (not infected)	A patient with no known diagnosis of HCV infection before the date of implicated surgical procedure at facility A or B, and who was both anti-HCV negative and HCV RNA-negative when tested during the investigation.
HCV status unknown	A patient with no known diagnosis of HCV infection before the date of implicated surgical procedure at facility A or B, and who did not undergo HCV testing as part of the investigation.