Swine flu: 'There are two weeks where it could go either way'

Swine flu: 'There are two weeks where it could go either way'
As the scientific community admits the world is overdue for a pandemic, will the outbreak of swine flu find Britain prepared, asks Neil Tweedie.

by Neil Tweedie
Last Updated: 1:30PM BST 28 Apr 2009

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Swine flu is a variant of the H1N1 strain which causes seasonal outbreaks among humans Photo: Getty
Buy shares in pharmaceuticals, sell airlines and travel operators – well, at least for the next one or two weeks. It will take about a fortnight for the threat presented by swine flu to become clear – the scaremongers can scare away to their hearts' content for the next few days but neither they nor anyone else knows if the outbreak in Mexico City represents the beginning of a global influenza pandemic.

"Flu is like fire," says Angela McLean, director of the Institute for Emerging Infections at Oxford University. "You have an outbreak and it spits out sparks. You then have to wait to see whether the sparks die out or start new fires."

Nearly 150 people in Mexico are thought to have died after contracting a new version of the flu virus, and yesterday two cases were confirmed in Scotland, as another 22 remained under observation in the UK. There are other confirmed cases in the United States, Canada and Spain; and suspected cases in New Zealand, Israel and Colombia. Meanwhile, the Russians banned imports of US and Latin American pork (for no good reason).

The version in question is a variant of the H1N1 strain responsible for seasonal outbreaks in humans but containing genetic ingredients from strains that normally affect birds and pigs. It is virtually certain that the new variant can be transmitted between humans – otherwise all those infected would have to have been in contact with pigs. Currently, that makes it more of a threat than the avian flu strain H5N1, which has killed scores of people in South-East Asia. Although H5N1 may one day mutate into a human-to-human strain, it has not yet done so – all those who died worked closely with birds.

Influenza is the most adaptable of viruses, constantly evolving to outwit human attempts to combat it. There were three flu pandemics in the 20th century: the "Spanish influenza" outbreak of 1918, which some scientists think may have evolved from swine flu and killed between 40 and 50 million people worldwide; the Asian influenza pandemic of 1957; and the Hong Kong outbreak of 1968. Between them, these may have been responsible for four million deaths. Received opinion has it that the world is overdue another one. So what could the Mexican outbreak mean for Britain?

The doctors, scientists and civil servants responsible for managing an outbreak have a problem: they can raise the alarm now and be accused of over-reacting if Mexican flu remains just that; or they can wait and be accused of under-reacting when the British economy, already in intensive care, goes into cardiac arrest as hundreds of thousands of workers take to their beds.

According to a Cabinet Office briefing paper, a flu pandemic could reach the UK within two to four weeks of an outbreak. Once here, the virus would spread to all major population centres within one or two weeks. Peak infection would occur seven weeks after its arrival.

The department states: "Depending upon the virulence of the influenza virus, the susceptibility of the population and the effectiveness of counter-measures, up to half the population could have developed the illness and between 50,000 and 750,000 additional deaths could have occurred by the end of the pandemic in the UK."

The latter is presumably based on the apocalyptic assumption that half the UK population of 61 million contracts flu and then suffers the 2.5 per cent mortality rate seen in 1918. This compares to mortality rates of 0.5 per cent in 1957 and 1968. Nevertheless, a flu pandemic could induce economic dislocation in the United Kingdom on a crippling scale, and the jitters have already begun.

The travel industry copped it first, with shares in airlines plunging and stocks in cruise lines sinking. Shares in British Airways, Carnival Cruise Lines, Intercontinental Hotels and Thomas Cook all headed south as the European Union commissioner for health advised against all but essential travel to affected areas of Mexico and the United States. That announcement was bound to drown out President Obama's expression yesterday of "concern rather than alarm" over the outbreak. The share movements could not be justified by available evidence, but then, when did that stop the speculators?

In an assessment of 2005, the World Bank warned that a pandemic could cause a loss of 2 per cent in global GDP over the course of a year, due to reduced productivity through absenteeism. Tourism and the restaurant and hotel sectors would be hit severely as people sought to stay away from each other, while health services would be overwhelmed by those seeking help. The Department of Health believes a flu pandemic would cost Britain up to £7 billion in lost GDP if a quarter of employees were affected, and double that if half went on sick leave at some point – a more likely figure. Hospitals and surgeries would be swamped: pneumonia cases could easily outstrip the 110,000 acute and 1,800 intensive beds available in England and Wales.

A specialist in acute medicine based in London told The Telegraph that he had made preliminary plans to quarantine himself from his wife and three children if the flu outbreak proves to be serious and he is treating patients.

Some 12,000 people die from influenza in England and Wales each year but because the overwhelming majority are elderly that fact tends to escape the general population. The outbreak of 1918 differed from the norm in that young adults and those in early middle age, the 25-40 age group, died in the greatest numbers. The theory is that their strong immune systems over-reacted to the flu strain with fatal results. Post-mortem examinations uncovered severe haemorrhages in lungs unlike anything seen before. Some 230,000 people in Britain are believed to have succumbed to the flu pandemic, a painful toll given the three quarters of a million claimed by the First World War.

"Even in an outbreak involving low mortality, there could be real problems in maintaining services," says Prof McLean. "Schools could close for extended periods, for example. Then there is the "milk in Tesco" question. The just-in-time ordering system of supermarkets may have made us more vulnerable to stoppages through illness. I heard one figure suggesting there are eight hours worth of milk in London at any one time."

The good news is that Britain is one of the best-prepared nations with regard to stocks of the anti-influenza drugs Tamiflu and Relenza, which would supply some protection against a new strain. And, of course, the Mexican outbreak could go the way of Sars and bird flu, viral outbreaks which claimed lives at an alarming rate initially but then failed to spread.

When swine flu broke out at a US army base in 1976, predictions of a cataclysm accompanied it. F David Mathews, the US health secretary, warned: "The indication is that we will see a return of the 1918 flu virus – that is the most virulent form of the flu. The predictions are that this virus will kill one million Americans in 1976.''

Thankfully, he was wrong. Only one person died and the outbreak spontaneously ceased.

"There is a difference between being able to transfer between one human being and another, and being able to do it efficiently," cautions Professor McLean. "This strain may not be very infectious. What matters is how much virus these people are shedding and for how long – for how long are they coughing and sneezing."

"We can't know for weeks what proportion of people catch it and what proportion die from it. This might turn out to be nothing – outside Mexico."

Even if the Mexican strain spreads to the UK, people are fitter and better fed than they were in 1918. And antibiotics mean the secondary infections that often kill flu sufferers can be seen off. Still, Prof McLean believes caution is the best policy.

"You could say that it is better to over-react and then retreat. Eating humble pie at a later date is preferable to reacting too slowly and too late because outbreaks are easier to control early on."

Even in 1918, when transport was slower and scarcer, Spanish flu managed to spread around the world, reaching – and devastating – the remotest Inuit villages in five months. The jumbo jet and the era of mass travel has made influenza's task much easier.

"If this is a pandemic, we should begin to see these newly seeded epidemics growing in different countries in one or two weeks," says Prof McLean.

"Are we overdue for one? I think I would agree that we are. It's been an awfully long time.

"These are the two weeks where it really could go either way. It's a question of watch this space."


http://www.telegraph.co.uk/comment/5232571/There-are-two-weeks-where-it-could-go-either-way.html



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