Flu deaths analyzed for future lessons

By Dr. Ananya Mandal, MDOct 27 2010

A new report has looked at all of England’s swine flu deaths in children under 18 during the 2009 pandemic. Researchers found that there was a higher risk of dying from the influenza A H1N1 strain of flu among certain groups of children, such as those with pre-existing conditions and those of a Pakistani or Bangladeshi background. However it was unclear why.

The study was conducted by the Department of Health and the National Patient Safety Agency, including Sir Liam Donaldson, who was Chief Medical Officer for England during the recent swine flu pandemic and Dr Nabihah Sachedina, his former clinical adviser at the department of health. The study was funded by the Department of Health and published in the peer-reviewed medical journal The Lancet.

As a background the authors say that overall death rate from seasonal flu is low and it predominantly affects people above 65 years old. However, the recent swine flu pandemic affected children disproportionately.

All deaths were recorded during the flu pandemic and further deaths were identified through cross-checking of records held by the Regional Directors of Public Health and by the Health Protection Agency’s influenza reference centers. All the fatal cases were assessed by a member of the Chief Medical Officer’s clinical team. A death was related to influenza A H1N1 if there was laboratory evidence of infection with this virus or if H1N1 infection was recorded on the death certificate. A pediatrician from the Chief Medical Officer’s team interviewed the child’s doctor about pre-existing disorders and medical history of the child, their symptoms and the clinical course of their flu.

Results showed that a total of 70 child deaths related to pandemic influenza A H1N1 occurred in England between June 2009 and March 2010. All of these cases were confirmed by laboratory testing. This corresponds to a rate of six per million of the population. There were a similar number of boys (31) and girls (39) who had died. Deaths were reported in children aged between 3 months and 17 years, with an average (median) age at death of 7 years.

Six of the children who died were Bangladeshi or British Bangladeshi. This corresponds to a rate of 47 deaths per million of the Bangladeshi population in the UK. There were also 11 deaths in Pakistani or British Pakistani children, which corresponds to a rate of 36 per million in the population. There were no differences in pre-existing health conditions between the children from these three ethnic groups.

Among the 70 deaths, 19 occurred before the children could be admitted to hospital. Forty-five of the 70 children received the antiviral drug oseltamivir (Tamiflu). Seven of the children received Tamiflu within 48 hours of the onset of their symptoms. On average (median), the children received Tamiflu five days after the onset of their symptoms. The latest that Tamiflu was given was on the seventh day after symptom onset. Two of the 45 children who received Tamiflu had swine flu that was resistant to the drug.

The researchers suggested that their findings support the vaccination of children against pandemic influenza A H1N1.

In an editorial on the Lancet site, two experts from Canada, Dr Robert Fowler of the University of Toronto and Dr Philippe Jouvet of the University of Montreal write, “With the luxury of post-pandemic hindsight and with the findings of Sachedina and Donaldson, we now know that the 2009–10 H1N1 infection was associated with severe illness and death in greater numbers of children and young adults than previous influenza seasons with other influenza viruses. Any talk of over-reaction to 2009 H1N1 virus might lead to an under-appreciation of the very real risks of influenza. The 2009 pandemic was not nearly as severe as feared, but might have been even less so with increased vaccination availability and uptake.”