Popular people “less likely” to survive pandemic

THE more popular a person is the more likely they are to get diseases and illnesses.

Speaking at the Surviving the Next Pandemic event, at the Edinburgh International Science Festival, Dr Deirdre Hollingsworth, an epidemiologist at Warwick University, will explain how the risk of surviving the next pandemic, or even catching flu, depends on the numbers and types of contacts a person has.

Busy and popular people who come into contact with more groups of people are far more at risk than those with less friends or working at home.

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Dr Hollingsworth, who was part of a team which advised the World Health Organisation on the likely extent and severity of the 2009 swine flu outbreak, said: “Your risk of acquiring an infectious disease depends on the numbers of contacts and the types of contacts you have.

“For example, catching flu needs different types of contacts. If you were on a train with someone very close, breathing the air for lot of the time, you’d have a bigger chance of contracting it than if you were working at home. While there is a good chance of transmitting it to your household, if you talk to a lot of people during the day you’re exposed to a lot more contacts.”

“But in some ways being popular might benefit your health because being exposed to so many germs has helped you develop immunity.

She said the same process could apply to a number of illnesses ranging from colds and sore throats to those which many people in the UK have been vaccinated against - tuberculosis, mumps, whooping cough, meningitis and diphtheria.

Dr Hollingsworth, will explain why more use should be made of scientific modelling to work out who should get access to vaccines.

“We have to prioritise and try to understand what type of disease we are dealing with. If you catch flu you are likely to infect one or two other people so we’d need to vaccinate 50 per cent of the population.

“If there is a disease where 80 per cent of the population are vaccinated the chances of you spreading it on are low - so we need to find out what the threshold level,” she added.

Vaccination

The Surviving the Next Pandemic is sponsored by the Edinburgh-based International Centre for Mathematical Sciences ICMS) which runs the Maths for Planet Earth international project which uses maths to help tackle human problems.

Professor Keith Ball, scientific director of the ICMS, said mathematical modelling provided an efficient use of resources.

“You might think it would be more natural to vaccinate those most at risk - the old, babies, the sick.

“But resources are limited and we want to stop disease spreading quickly so we target those who provide links between lots of groups. So it makes sense to target those who form “hubs” between groups of people. If we stop the disease passing through these hubs, then we stop the disease.

Professor Ball said that the definition of a “popular” person in the work sense would be someone like a teacher, who formed a “hub” for many others.

“If the teacher doesn’t get the illness or disease they can’t pass it on.

“But there may be other people who do not have many connections but who are connected themselves to the teacher. This is why a subtle approach is needed to identify the links.

“We can use mathematical modelling to identify the typical number of connections of a range of people from office workers, chief executives to children. When this is explained I think the public get a far better understanding that it is no the elite - the government, chief executives or wealthy people - who are getting special treatment just because of who they are.”

Dr Martin Donaghy, medical director of Health Protection Scotland, the Scottish Government agency which co-ordinates measures to protect people from infectious and environmental hazards, said a range of factors were examined for vaccination programmes.

“Mathematics is absolutely key. But we also have to have an understanding of the disease and how it spreads and its impact on health which will influence the decision making factors.

“To get the mathematics right we need input from a whole range of professionals. To run such a model we need data of observations to monitor and research what is going on.

“Such modelling is detailed and complex. We do a little bit ourselves but mainly work with our partners in England. The findings then go the Joint Committee on Vaccination and Immunisation and then to health departments who then decide what to do.”

“Nowadays a lot of the decisions on new vaccines and the extent to which we use old ones is based on “cost effectiveness” and quality of the years of life added.”

• Surviving the Next Pandemic - event at Edinburgh International Science Festival - Tuesday 2 April, 8pm National Museum of Scotland Auditorium. Tickets £8/£6. www.sciencefestival.co.uk