Swine flu in England less deadly than first feared

Tuesday 15 December: The Chief Medical Officer of England says low death rate is “fortunate”.

A study led by doctors in the UK government has found that swine flu in England is less deadly than initially thought. Professor Sir Liam Donaldson, the Chief Medical Officer for England, writing in the paper published by the BMJ, said: “The first influenza pandemic of the twenty-first century is considerably less lethal than was feared in advance.”

In June this year, the World Health Organization declared the first flu pandemic in 40 years. The new influenza A H1N1 virus reached the UK about a month after it was first detected in Mexico. To understand better the health risks associated with this new strain of flu, the Department of Health analysed the data of swine flu deaths. From this, they were able to work out that 26 out of every 100,000 people in England who had swine flu died from the virus.

These numbers compare favourably with previous flu pandemics. The most recent pandemics in 1967/8 and 1957/8 were estimated to have death rates of 200 people in every 100,000. The deadly Spanish flu of 1918 was estimated to have a death rate of 2000 to 3000 people in every 100,000. But these previous estimates are probably far less reliable than current estimates owing to better reporting methods used these days.

However, Professor Donaldson cautioned: “A lower population impact than previous pandemics is not a justification for public health inaction when death, serious illness and admission to hospital can be prevented.”

The Department of Health also used the data to learn more about who is most at risk from the virus. Men and women were equally affected. People over 65 were less likely to get swine flu, but more likely to die from it compared with those aged five to 24. And most people who died from swine flu had an underlying disease. Overall, people in the high-risk groups were nine times more likely to die from swine flu than healthy people. This led Mr Donaldson to conclude: “Our findings lend support to a vaccination strategy that prioritises high-risk groups.”

Dr Sneh Khemka, medical director for Bupa International, said: “This is good news. I’ve been following the pandemic closely around the world this year, and this analysis from the UK is probably the most reliable yet. It confirms that this isn’t the deadly pandemic flu that people feared. What’s important now is to make sure that the people most at risk in the Northern hemisphere are vaccinated during the winter months to help prevent them getting ill.”

Key facts

High-risk groups for pandemic flu are people with:

chronic lung, heart, kidney or liver disease
a chronic neurological disease
a weakened immune system, such as those who have HIV/AIDS, or those who are taking medicines that suppress the immune system
diabetes
asthma

Also at risk are:

pregnant women
children under five years old
people aged 65 and over

Priority groups for the UK vaccination programme are:

people aged between six months and 65 years who are usually at risk of complications from seasonal flu
pregnant women
people with weakened immune systems, such as those who have HIV/AIDS, or those who are taking medicines that suppress the immune system
people aged 65 or over who are at risk of complications

Read the study

Donaldson LJ, Rutter PD, Ellis BM, et al. Mortality from pandemic A/H1N1 2009 influenza in England: public health surveillance study. BMJ 2009, 339:b5213. doi:10.1136/bmj.b5213
http://dx.doi.org/10.1136/bmj.b5213