Ga. Code § 15-12-172
If at any time, whether before or after final submission of the case to the jury, a juror dies, becomes ill, upon other good cause shown to the court is found to be unable to perform his duty, or is discharged for other legal cause, the first alternate juror shall take the place of the first juror becoming incapacitated. Further replacements shall be made in similar numerical sequence provided the alternate jurors have not been discharged. An alternate juror taking the place of any incapacitated juror shall thereafter be deemed to be a member of the jury of 12 and shall have full power to take part in the deliberations of the jury and the finding of the verdict. Any verdict found by any jury having thereon alternate jurors shall have the same force, effect, and validity as if found by the original jury of 12.
OCGA § 15-12-172