Immunogenicity of a live-attenuated human rotavirus RIX4414 vaccine with or without buffering agent

Aim: The lyophilized form of the human rotavirus RIX4414 vaccine (Rotarix™) is usually reconstituted with a liquid calcium carbonate (CaCO3) buffer and administered orally. However, errors in the reconstitution could occur (e.g. reconstituted with water instead of CaCO3 buffer) or the buffer might be temporarily unavailable in few instances. This study was conducted to evaluate the immunogenicity of the RIX4414 vaccine if the vaccine was reconstituted with other agents (e.g. water) instead of CaCO3 buffer. Methods: Healthy infants aged 6–12 weeks, received two oral doses of the RIX4414 vaccine/placebo, reconstituted either with injectable water or CaCO3 buffer according to a 0, 2 month schedule. Seroconversion rates in terms of anti-rotavirus Immunoglobulin A (anti-RV IgA) antibody levels (cut off: ≥ 20U/ml by ELISA) and vaccine take were calculated 2 months post-Dose 2. Solicited and unsolicited symptoms reported during the 15- and 31-day follow-up period after each dose and serious adverse events (SAEs)...