Swine flu: still a looming threat?
Was the threat of swine flu over-estimated, and do we really need to vaccinate everyone now? Rada Rouse reports.
HYPE or hoax? Whatever the swine flu pandemic was, a lot of people believe it was never a deadly threat.
Earlier this year, the chair of the Council of Europe’s health committee, Dr Wolfgang Wodarg, forced an inquiry into the continent’s multibillion dollar expenditure on swine flu vaccine, saying governments had been hoodwinked by pharmaceutical companies wanting to make big bucks.
Worse, he accused the WHO of being in cahoots with Big Pharma and pushing the pandemic panic button before the mild nature of the H1N1 2009 virus became clear.
As “pandemic hoax” began appearing on blogs and news sites around the world, the WHO announced an inquiry into its own handling of the pandemic but, along with pharmaceutical manufacturers, rejected the conspiracy theories about improper commercial influence, and defended its preventive strategy.
“We do not wait until [global outbreaks] have developed, and we see that lots of people are dying,” WHO special adviser on pandemic influenza, Dr Keiji Fukuda, stated.
This crystallises the dilemma for governments: if they move into pandemic mode and the virus is not a killer, they are accused of wasting money. If they stall and the virus does turn out to be a killer, they are accused of abrogating their responsibility.
Australians, like the rest of the world, are reviewing the appropriateness of the national response.
In a debate in Respirology, Perth pulmonary diseases specialist Professor Grant Waterer wrote that the Australian public health response must be declared a failure, having failed to prevent widespread transmission in the first place (2010;15:51-56).
Rejecting the proposition, Sydney thoracic physician Professor Christine Jenkins suggests that the measure of failure would be excess mortality, higher attack rates than elsewhere and extreme disruption to non-flu-related healthcare delivery.
Seeing school closures, quarantine and mass testing of suspect cases as excessive is “an easy position to take in retrospect”, she wrote.
Now, as the southern hemisphere heads into autumn, federal and state governments are wondering how to motivate a cynical population to protect itself.
According to preliminary Government figures, only 20% of Australian adults took up the offer of free vaccine from 30 September last year.
A key opponent of mass vaccination, microbiologist and infectious diseases specialist Professor Peter Collignon from the Australian National University, warns multi-dose vials (MDVs) carry a risk of infection unless handled properly.
People who are clearly at risk – the immunocompromised, or pregnant women – should have the trivalent seasonal vaccine, he says.
“At the end of the day, for most people, this virus is very similar to seasonal influenza,” he says.
“The thing about mass vaccination is you have to look at whether we might cause more harm from the vaccine than we prevent.”
He says rare reactions such as anaphylaxis become a consideration when millions of people are being vaccinated, and research suggests that around 20% of children experience mild to moderate side-effects after the swine flu vaccine.
As of 31 December 2009, the TGA had received eight reports of possible anaphylaxis following vaccination with Panvax. It has determined that, based on distribution figures for the vaccine (about six million doses distributed), the current observed rate of anaphylaxis is “within the range expected for anaphylaxis post-immunisation”.
However, while Professor Collignon’s views about MDVs are backed by the Australasian Society for Infectious Diseases, other experts suggest he is wrong to reject jabs for younger, healthy people.
Professor Robert Booy, head of clinical research at the National Centre for Immunisation Research and Surveillance, points out that it is the relatively young – those under 60 years – who were hardest hit by H1N1, whereas seasonal flu brings down the elderly.
In Australia, around 200 people have died from the pandemic virus, and internationally it has killed around 16,000.
Many point out this is far short of the hundreds of thousands predicted last May to succumb globally, and for Australia, far fewer than the accepted annual seasonal influenza toll of 2000 deaths.
However, Professor Booy cautions that the swine flu toll and annual seasonal mortality figures cannot be compared, as the latter is only an estimate based on excess mortality from complications.
'MILD VIRUS' MYTH
Another myth that frustrates communicable diseases experts is the belief that because the majority of H1N1 cases are mild, we’re dealing with a mild virus.
A mild virus, they say, does not fill intensive care wards to capacity as occurred in Australia last year.
Associate Professor Steve Webb, from the University of Western Australia, headed a collaborative investigation of critical care services in Australia and New Zealand – the ANZIC study – to look at the impact of H1N1 last winter.
It found that nearly a third of patients (31.7%) admitted to ICU because of pandemic flu had no known predisposing factor1.
The proportion of patients who died in hospital was no higher than that previously reported among patients with seasonal influenza A admitted to an ICU, the study found.
However, these patients are usually elderly, whereas 90% with H1N1 were younger than 65, with most admissions occurring in the 25-49 age group.
Anecdotally, Dr Webb says, there were more hospital admissions than usual for severe community-acquired bacterial pneumonia.
And there is good evidence on viral pneumonitis due to influenza A, showing that the number of ICU admissions was 15 times that of recent years, he says.
In a letter to GPs, chief medical officer Professor Jim Bishop stated there were 700 ICU admissions with viral pneumonia in 2009, compared to “around 55 per year for the last five years”.
Dr Webb says, at the peak of the epidemic, between 10% and 20% of ICU beds in each state were occupied by patients with pandemic influenza, a surge forcing the cancellation of elective surgery and double shifts for staff.
“It is notable that even a mild pandemic stretched the ICU system – almost to breaking point,” he says. “Intensivists with 30 years’ experience have told me that they’ve never experienced anything like it previously.”
While these considerations may be cited as underpinning the current push for vaccination, with millions of doses of taxpayer-bought vaccine languishing in stockpiles, there are “other factors, both commercial and political” at play, Professor Collignon says.
The question GPs will likely face from patients is: Do I really need to be vaccinated?
According to Professor Bishop, people need to know that pandemic flu differs from seasonal flu “in important ways”.
For example, the median age of death for seasonal flu is 83 years, while for pandemic flu it is 53 years.
Comparing seasonal and pandemic mortality statistics, the WHO’s Dr Fukuda says, is like “comparing apples with oranges”.