If there are any vacant seats left after the counselling rounds then the govt. of the respective state will open up the seats for the allottment for the candidates. But the declaration of the further rounds of the admissions in medical courses and for the vacant seats depend upon the authority counducting the admissions. Rejection of the candidates could be due to certain reasons and not fulfilling the eligibility criteria could also be the one reason. But if the vacant seats are to open then they will and nothing to worry about that.