Carter developed a fever late Thursday, and aUNC Hospitalsspokesperson says it got worse during the night.
To battle the fever, Carter is on IV antibiotics. The antibiotics interfere with taking medication to protect Carter's body from rejecting the new organ. UNC's Karen Stinneford says Carter cannot take both medications at the same time.
Stinneford says the kidney transplant operation will not happen before Christmas because the line for the student's dialysis has become infected, and doctors want to give that plenty of time to clear up.
Faculty and staff held a prayer breakfast for Carter and Smith Friday morning at Max Abbott Middle School.
"She's a brilliant lady, an amazing educator," said Alana Warren, a teacher. "He is not only is lucky to have her kidney but he is lucky to have her as her teacher."
Teachers have also shared information about organ donation with students.
"Some of the children, who are not able to make that decisions for themselves at this time, are impressing upon their parents to be organ donors," said principal Myra Holloway.
Students in Cumberland County are about to go on Christmas break. Carter and Smith had hoped to use the time to recover.
The transplant surgery has not been rescheduled, but the latest information available suggests it will not take place until after the New Year.