Over the next month, governments worldwide, including the US and Europe, will be rolling out mass vaccination programs against the pandemic (H1N1) influenza or swine flu. They are doing so on the basis of a consensus of expert opinion in the public health community based on data provided by the World Health Organisation, an organisation with expertise dedicated to the surveillance and prevention of influenza developed over decades.
Claims that swine flu can be dismissed as a mild disease are not supported by the facts. In Australia, more than 700 people with swine flu have been admitted to ICUs around the country, putting enormous pressure on our already burdened public hospital system. Of the approximately 10% of these patients who ended up on life-support, the average age was just over 30. Several of those admitted were pregnant, four of whom have since died. Others have lost their babies or endured premature labour.
It is clear that even a so-called mild flu can have a catastrophic effect in a subset of people when spreading through an unvaccinated population. In a normal flu season these statistics are unheard of, and could be seen again if the so-called second wave, which is already appearing in college students in the US, returns to Australia over the next few months.
Initial data from a clinical trial in Australia of its H1N1 influenza vaccine have shown that with an efficacy rate of more than 95% in adults, vaccination will stop this epidemic in its tracks.
Several claims have been made in Crikey about the swine flu vaccine that warrant a response. Far from having had “less than optimal safety and efficacy studies performed”, the swine flu vaccine has had more testing than the seasonal flu vaccines (with which we have four decades of safety and efficacy experience), to which it is identically formulated — the only difference being that it contains one flu strain instead of three. Additional clinical trials were done in this case to ensure that the dose used is adequate given that the virus has spread rapidly from animals into a human population.
It has been suggested that there was a higher rate of adverse events seen in the CSL clinical study than for some other vaccines. In fact, the adverse event profile noted was no different than that seen with seasonal flu vaccines, with no serious side-effects observed. The use of multi-dose vials that will be used worldwide to administer H1N1 vaccine, and that are used commonly by health professionals to administer products such as Botox, caused no problems. Contrary to some media reports, there is no sharing of needles or syringes in the use of the vials, and if used correctly, transmission of blood-borne organisms from patient-to-patient is impossible.
Professor Peter Collignon speculated in his article that 30% of 18-65 year-olds are already immune to swine flu as a result of previous infection. While the Australian clinical study revealed that there is some baseline immunity to this H1N1 strain in about 30% of this age-group, in most cases, this is insufficient to prevent infection, and is probably due to infection with similar strains in previous seasons.
Finally, the issue of the link between Guillain-Barre Syndrome (GBS) and the 1976 vaccination program in the US deserves a mention. The assertion that this represents a significant risk in this current vaccination program is inaccurate. Not only is the circulating strain of H1N1 totally different than the 1976 swine flu, the modern vaccine that we now use is different from the crude vaccines used 30 years ago. It should be made clear that GBS is an immune system disease that occurs after infection and very rarely after vaccination. It can thus occur as a result of infection with influenza itself — the incidence of GBS in Australia is about 1-2/100 000 people regardless of rates of vaccination with any vaccine.
A response to this issue published in the British Medical Journal this month quotes Dr Michael Skinner, senior lecturer in virology at Imperial College in London:
“it (GBS) clearly is associated with infection and it may well be that it does get more associated with a particular vaccine, but the only one we’ve seen is that one in 1976, if at all,” He added: “Even if you take the worst case scenario, from the vaccine and from the infection, you’re something like a thousandfold better off with the vaccine that you would be from the infection”
Fortunately common sense has prevailed in Australia and the government deserves commendation for getting on with the vaccination program. Those who work with influenza show no complacency about the swine flu.