Immunogenicity and safety of a low passage level bovine rotavirus candidate vaccine RIT 4256 in human adults and young infants.

A candidate rotavirus vaccine RIT 4256, derived from Nebraska calf diarrhea virus by 21 tissue culture passages, was tested in humans and compared with the RIT 4237 vaccine derived from the same stem virus by 147 tissue culture passages. The low passage strain RIT 4256 was first tested in adult volunteers for immunogenicity and safety: a serological response was seen in 9/18 (50%) vaccinees; three subjects had a mild fever reaction attributable to the vaccine. In 6 month old children the RIT 4256 vaccine elicited a serological response in 12 of the 21 (57%) seronegative recipients; two children had a possible fever reaction from the vaccination. In newborn infants a serological response following vaccination was detected in 19/41 (46%) of the recipients of the RIT 4256 and in 19/40 (48%) of the RIT 4237 vaccine; none of the newborn infants had any reaction from either vaccine. It is concluded that the low passage strain RIT 4256 is not more immunogenic than the high passage vaccine RIT 4237 in humans. The vaccines do not differ in clinical reactogenicity for man.