LAUSR

https://jkms.org We read with interest the paper by Hong et al.1 about the effectiveness of one-dose universal varicella vaccination (UVV) among Korean children. In the first birth-cohort study among Korean children, the authors reported a moderate level (49.9–86.1%) of one-dose vaccine effectiveness (VE) against varicella. The authors’ finding is in strong contrast with a low level (13.0%) of varicella VE reported in a previous case-control study.2 But it was generally in line with our position3, 4 based on a case-coverage simulation analysis that the real VE against varicella in the previous case-control study would have been 65–90% if selection bias would have been corrected.