A 67-year-old woman who developed generalised weakness after receiving the human swine flu vaccination suffered from acute disseminated encephalomyelitis - a neurological disorder involving inflammation of the brain and spinal cord.

She complained about leg weakness on January 12 after receiving the jab on December 23. She came down with a fever, headache and vomiting on January 15 and was hospitalised the same day. She is now in critical condition.

Dr Patrick Li, a member of an expert group studying illness in people who have received the vaccination, said today the woman had no encephalitis symptoms when she was admitted to hospital and was initially suspected to have Guillain-Barre Syndrome.

"However, subsequent investigations did not support such diagnosis. She later came down with a fever, septicaemic shock and renal failure. She was transferred to the intensive care unit and was later confirmed to have acute disseminated encephalomyelitis."

Dr Li said her illness is more likely related to serious infections and more tests will be conducted.

Noting the vacccination was unlikely to have caused the incident, expert group chairman Dr Chan Man-chung urged people to have confidence in the Government's human swine flu vaccination programme.

Forty-two severe human swine flu cases have been recorded since the programme started on December 21 and 12 of them died. Sixty-seven people in Hong Kong have died from the disease.