It is difficult to predict whether flu outbreaks will turn into pandemics but we still need to be prepared, writes CLAIRE O'CONNELL
‘Flu pandemic set to strike in autumn,” rang headlines in the British press last week after a virologist forecast a surge of influenza type A (H1N1) infections there after the summer break.
“Problems at the moment are fairly low, with schoolchildren and the odd sporadic case in the community,” Prof John Oxford from the University of London was reported as saying. “But when children go back to school in September the virus has an opportunity, and normally it takes it.”
But making predictions about pandemics is something of a dark art, and while an up-swell of H1N1 infections in the winter flu season is possible, experts have to walk a tightrope between unfounded speculation and being prepared for what may come.
So as the World Health Organisation teeters on the brink of announcing a global pandemic – what can we really tell about the future of influenza type A (H1N1)?
“People can speculate and say what they want, but no one really knows,” says Prof Billy Hall, director of the National Virus Reference Laboratory at UCD and chair of the National Pandemic Influenza Expert Group. “This virus could stay around, it could be back in the winter season, it could be the same mild illness, it could be a more severe illness, or it could disappear.”
To date, 11 cases have been confirmed in the State, and while it is impossible to predict, we will probably see that tally rising over coming months, says Dr Tony Holohan, chief medical officer with the Department of Health and Children.
“A likely scenario is that cases would continue to occur over the summer but because transmission of influenza and similar infections is less likely in the summertime we are not likely to see a significant increase beyond the kind of level we are seeing at the moment,” he says.
Officials are continuing to monitor influenza viruses, with many eyes trained on the southern hemisphere, currently in its winter – Australia and Chile have reported several hundred cases of influenza type A (H1N1).
But the relative calm of few cases worldwide and mostly mild symptoms should not breed complacency, nor should the authorities be thought to be crying wolf. “We need to continue to plan on the basis that this is likely to occur,” says Holohan.
Ireland has a multi-level national pandemic plan, drawn up when avian flu H5N1 threatened a pandemic. Bird flu didn’t take off then, but the plan still stands, according to Holohan.
“Everything that needs to be in place will be, vaccine arrangements, anti-viral arrangements and practical arrangements for information,” he says.
The State has stockpiled enough anti-viral drugs to cover about 50 per cent of the population. When taken within 24-48 hours of the onset of symptoms, anti-virals can reduce the severity of the disease. And to date, influenza type A (H1N1) appears to be susceptible to those drugs.
Meanwhile, if the WHO calls a global pandemic, a vaccine will be developed against the strain – by infecting chicken eggs with live attenuated strains of the virus – and Ireland is in the queue to receive doses when they become available, about four to six months later.
“The HSE has a contract in place with two companies and in the event that a pandemic is declared they will provide us with 7.7 million doses of vaccine,” says Holohan, although he could not disclose the vaccine cost or providers.
“Two doses for each person would be the recommendation,” he adds, noting that vulnerable people such as those with underlying medical conditions and frontline health workers would be prioritised for the jabs.
But what if the virus changes over time – will the original vaccine still protect against infection?
“If at some stage it changes its morphology to become a more virulent virus that requires a newer, different vaccine, that’s a scenario we would have to face,” says Holohan.
Making a vaccine is a practical approach, despite the unpredictability, according to Luke O’Neill, professor of biochemistry at Trinity College Dublin.
“The WHO has to behave responsibly and even if the threat of this strain is difficult to predict, overall ‘normal’ flu kills a lot of people and so it makes sense to prepare vaccines against new flu strains that are highly infectious – which this one is – even if it’s mild. It will have a mortality rate associated with it although this is difficult to predict as the number of deaths is low.”
But even with an arsenal of anti-viral drugs and vaccines at the ready, experts insist that personal hygiene is a key element in the strategy in the event of a pandemic. “The vaccines and anti-virals are our back-ups,” says Holohan. “The best line of defence we have against this is the actions that ordinary people take to prevent this from transmitting among their own communities and families.”
He urges people to keep the information leaflet distributed by the HSE and on its website (www.hse.ie) for reference.
“The simple message is that people should use a tissue to blow their nose, cover their nose and mouth and dispose of the tissue in a bin, always wash their hands afterwards and stay away from people if infected.”
Holohan says that even a mild flu will keep people off work, and businesses should put continuity plans in place – guidelines are on the Department of Trade Enterprise and Employment website (www.entemp.ie).
“I’d be urging people to use the time we have at the moment; we don’t know what is down the road, so use the time when the pressure isn’t on to get this planning work done.”
Holding back the flu
Influenza A/H1N1 continues to spread around the world, with 69 countries reporting nearly 22,000 cases and 125 deaths at time of writing.
The WHO has currently set the alert level to five, and a move to six would signify a full-scale pandemic.
"We are anticipating a change in the phase," says Dr Tony Holohan from the Department of Health and Children. But that doesn't necessarily mean the virus itself has become more dangerous, he notes.
"It is a description of the geographic occurrence of the virus, it's not a statement of new information as to its severity.
"And what will ultimately change the situation in this country is not just the WHO level but the pattern of cases we get in Ireland," says Holohan.
"Even if level six were to be declared tomorrow we still only have a very modest number of cases which have been contained, and our policy remains to actively seek out cases and treat them and contacts to delay the spread.
"We might get to delay it until we can get vaccine to significant amounts of the population."