Detailed kinetics of immune responses to a new cell culture-derived smallpox vaccine in vaccinia-naïve adults.

The aim of the present study was to investigate the kinetics of humoral and cell-mediated immune responses to a new cell culture-derived smallpox vaccine (CJ-50300, CJ Corporation, South Korea) in 18 vaccinia-naïve volunteers. All subjects achieved positive humoral immune responses (plaque reduction neutralizing antibody assay) 28 days after vaccination, and cell-mediated immune responses (ELISPOT assay) 14 days after vaccination. Humoral immune responses increased up to 28 days after vaccination and were maintained up to 56 days after vaccination. In contrast, cell-mediated immune responses increased up to 14 days after vaccination and steadily decreased to 56 days after vaccination [Clinical Trial No. NCT 00336635].