Three other students and a teacher are in the hospital with other illnesses.
The bulk of the group - 25 students and five teachers - has been quarantined in a nearby hotel for a week, but were expected to be released Thursday.
Each student was being held in a different room with a television and phone. Hotel employees make food runs for the students, who were not allowed to have personal contact with anyone - not even each other.
"In the hotel, they're kind of shouting across the hotel and calling each other," Callaway said Wednesday.
Employees at Beijing's swine flu command center and at the hotel say that the group was cleared for release Thursday. It was not clear when the hospitalized students and teachers would be released and allowed to return to California.
The group of 35 ninth-graders left for China on June 2. Before the quarantine, they climbed the Great Wall, explored the immense plazas of the Forbidden City and visited the Terra Cotta Warriors in the inland city of Xi'an.
The group had embarked on a river cruise to Three Gorges Dam when a handful of students and one teacher started feeling sick and saw a doctor on board.
Under the Chinese government's protocol, the students and teacher were taken to a nearby hospital when the boat docked. Callaway said she didn't know where the students contracted the virus. They didn't have flu-like symptoms before the trip, she said.
At the school campus tucked away in the hills in Carlsbad, no one would comment on Wednesday, and all questions were referred to Callaway. Messages were left for Eileen Mullady, the head of the school, and Rick Sapp, chair of the board of trustees.
Sapp told local television station San Diego 6 that his 15-year old daughter is among the students in the hotel.
"When I first initially heard the word quarantine, we all get that sinking feeling from the nature of the word," he said.
"She's upbeat. She understands she's in an unusual situation. She's doing what kids normally do. She is entertaining herself by reading a book."
Callaway said the group might hold an event on campus once they're home to mark the end of the school year, which culminated Tuesday.
After the river cruise, the group was scheduled to head to Shanghai and stay with local families before returning to California.
The trip is tied to the ninth graders' study of ancient history and water resources.
Pacific Ridge opened in 2007 as a college prep school beginning with the seventh grade.
Pacific Ridge School: http://www.pacificridge.org/