10 Feb 2010
The Expert Group on Serious Adverse Events with History of Human Swine Influenza (HSI) Vaccination has arrived at a consensus view on a suspected case of Acute Disseminated Encephalomyelitis (ADEM) with history of human swine influenza vaccination.
At its meeting today (February 10), the group considered that the clinical features of the patient were compatible with ADEM. Further investigations are underway to better delineate the cause of her illness. However, the expert group considered it unlikely that her illness had been caused by HSI vaccine.
The case was reported to the Centre for Health Protection on February 4, 2010.
The patient was a 67-year-old woman who developed generalized weakness on January 12, 2010, followed by fever and headache on January 15, 2010. She had undiagnosed diabetes mellitus and went into septicaemic shock and renal failure requiring renal replacement therapy. She is currently staying in the intensive care unit in critical condition.
Further magnetic resonance imaging examination of the brain done on February 1, 2010 showed features suggestive of ADEM. Other differential diagnoses include vasculitis, multiple infarcts and infection.
She received HSI vaccine on December 23, 2009 in a government outpatient clinic.
Locally, the exact incidence of ADEM is not known. From record reviews, the expert group noted that there had been at least one case that was preceded by seasonal influenza infection and another preceded by HSI infection in 2008 and 2009 respectively.
The expert group also learnt that between December 21, 2009 when the HSI vaccination programme started and February 9, 2010, there were a total of 42 severe HSI cases, of which 28 were male and 14 female. The affected persons were aged between 30 days and 85 years with a median age of 52 years.
Thirty of these cases, or 71.43 per cent, required admission to Intensive Care Units. Twelve of them died. The majority of them (35 of 42 severe cases and 11 of 12 fatal cases) fell within the target groups for HSI vaccination.