1.   Apparently, even a weakened SIV vaccine can mutate into disease-causing forms, Ruprecht said.

2.   At that time, federal health officials discussed the problem with medical experts and determined that there was no need to revaccinate those who received the weakened vaccine.

3.   Healthy people should not be re-immunized, even if they received the weakened vaccine, officials said.

4.   However, more recent findings have found that some monkeys injected with artificially weakened simian vaccine have died or become ill from simian AIDS.

5.   Kessler said the cause of the weakened vaccine was unknown and was being investigated.

6.   Participants who received the weakened vaccine had moderately lower amounts of antibodies to the Nanchang strain of influenza virus.

7.   People who have received flu shots are advised to call their health care providers to determine if they received the weakened vaccine.