The 31-year-old Beijing Olympian was isolated in hospital after reporting chest pains during the 10 kilometre run of the second ITU Triathlon World Championship race at Mission Beach on Sunday.
Doctors at Scripts Mercy Hospital in San Diego believed Kahlefeldt was suffering from atypical pneumonia and he would not be allowed to fly for at least another week, Triathlon Australia said in a statement on Thursday.
There was every chance Kahlefeldt could start light training in a couple of days, TA's high performance manager Michael Flynn said.
"Doctors will have to continue to monitor him and he has to be given the all-clear before he can fly. Once he has been cleared Brad can then hopefully join the Australian team camp in Majorca."
Kahlefeldt had been due to fly out for a training camp on the Spanish island on Monday in preparation for the next round of the ITU World Championship Series in Madrid on May 26 and 27.