Fiorina supporters were out drumming up support for their candidate when they heard the news.
"Obviously you want the best for somebody, and she's a fighter. I'm sure that she'll get over this and get right back out and campaign as hard as she can," says Burlingame resident Andrew Peceimer.
"I believe that she's a tremendous fighter and a brave woman, and she has been given a clean bill of health, so I think that she will do good," says Campbell resident Dayna Howell.
They were standing outside Cisco systems because inside was Democratic incumbent Sen. Barbara Boxer, fielding questions at an employee town hall meeting. Boxer's campaign staff would not make her available for an interview, but her campaign manager said in a statement, "We wish Carly Fiorina a speedy recovery and hope she is able to return to her normal schedule soon."
Fiorina's hospitalization impacted two of her campaign events, both in Southern California. Other politicians stepped in for her.
"Carly is upbeat," Deborah Bowker, her campaign chief of staff said in a statement. "Her doctors expect her to make a quick and full recovery and be back out on the campaign trail soon."
Fiorina was diagnosed with breast cancer in February 2009. She had a double mastectomy after undergoing chemotherapy and radiation treatments.
Hoang Do, M.D., is a surgeon specializing in breast procedures at O'Connor hospital and in private practice.
The hospitalization indicates to him treatment requires intravenous antibiotics. If severe, the infection could also lead to complications.
"If the infection is extending into the chest wall, or let's say the infection is extending to the implant or the tissue expander, then it may require removal to treat the infection, let it heal about six months later, then the patient can have reconstruction re-done," says Do.
Because of Fiorina's condition, ABC7 political analyst Bruce Cain, Ph.D., thinks Boxer may have to tame her campaign.
"She has to be careful at least in her personal statements and it may also mean, perhaps, this is a time to roll out some of her own positive ads and get away from the attack mode," says Cain.
Doctors tell ABC7 that the chance of infection for any surgery is about 2 percent. However, with radiation, the rate can increase to 7 to 20 percent due to tissue damage, as well as impaired healing.