Irb continuing review of a greater than minimal risk approved protocol that is currently enrolling subjects must:

: receive the majority support among the members who are attending the meeting. The review of research can be conducted at various measured intervals, however, it must not be less than once each year.

Explanation:

Thus The Institutional review board organizes these kinds of reviews of the researches. And for each research. the number of reviews must not be less than once each year. And if the risk is more, the number of reviews can be increased as well for ensuring 100% legitimate research outcome.