The opinion reached by the medical negligence review panel shall be admissible as prima facie evidence in the pending Superior Court action brought by the claimant, but such opinion shall not be conclusive and any party shall have the right to call, at said party's cost, any witness who appeared before or submitted reports to the medical negligence review panel as a witness. If called, the witness shall be required to appear and testify. Members of a medical negligence review panel shall have immunity from civil liability for all communications, findings, opinions and conclusions made in the course and scope of their duties prescribed by this chapter.