They did this in 1,800 elementary school children, so these are about eight year-olds.

于是科研人员给一千八百名,八岁左右的小学生分发疫苗

耶鲁公开课 - 生物医学工程探索课程节选

If you could take your five year-old or eight year-old in to get a vaccine that was orally administered instead of a shot that's a much easier thing to do.

如果你带着五岁或者八岁的孩子,去口服而不是去注射疫苗,那将会轻松许多

耶鲁公开课 - 生物医学工程探索课程节选