Trials of oral bovine and rhesus rotavirus vaccines in Finland: a historical account and present status.
Live oral rotavirus vaccine strain RIT 4237, derived from group A bovine rotavirus NCDV, was given to human volunteers in Tampere, Finland in 1982. Efficacy studies of this vaccine in 6-12 month-old children gave results characteristic of the performance of oral rotavirus vaccines in general: 58% protective efficacy against any rotavirus gastroenteritis and 82% against "clinically significant" gastroenteritis. Four trials of RIT 4237 bovine rotavirus vaccine, one trial of group A RRV-1 rhesus rotavirus vaccine, and one trial of rhesus-human reassortant rotavirus vaccines D x RRV and DS1 x RRV were carried out between 1983-1989. A meta-analysis of the protective efficacy of these vaccines indicated a 67% (95% C.I. 55-77%) efficacy against moderately severe rotavirus disease and an 81% (95% C.I. 60-91%) efficacy against severe rotavirus disease. There was no apparent difference between bovine and rhesus-based rotavirus vaccines in the protective efficacy against severe rotavirus gastroenteritis. Problems associated with the use of any oral rotavirus vaccine include acid lability of the vaccine virus, which requires buffering, and a slight but significant interference of oral poliovirus vaccine with the uptake of rotavirus vaccine. In the near future, oral heterologous rotavirus vaccines may be available for prevention of severe rotavirus gastroenteritis.