IL22 and infection: Cytokine concentrations did not differ between baseline and 6 months for IGRA NC, but there were significant increases in concentrations of all four of these cytokines from baseline to 6 months among IGRA C. Moreover, EC-specific IL-22 production was observed only in IGRA C at 6 months, suggesting that EC-specific IL-22 is a biomarker of infection in some household contacts of TB cases.