A giant experiment started in England on Thursday 23 July. The algorithm-driven free "prescription" of Tamiflu through the National Pandemic Flu Service is without precedent. Never before has an antimicrobial agent been used on such a vast scale without medical control.
It could be said that policymakers have only themselves to blame for making this inevitable. Pronouncements about pandemic planning in recent years – and the plan itself – for all practical purposes redefined a pandemic as a horror-laden event in which mortuaries would be overflowing, with people dropping dead in the street and normal civic functions grinding to a halt. So it is not surprising that when swine flu met the standard pandemic criterion – community spread in more than one continent – WHO was lobbied (unsuccessfully) by the UK to postpone its declaration and incorporate severity into its definition.
But in spite of all the subsequent pronouncements that swine flu is mild for most, causing an illness no worse than seasonal flu (which rarely hits the headlines and whose sufferers rarely get Tamiflu unless they are in high-risk groups), it appears that policymakers still considered that the public wanted more to be done. And the perception of Tamiflu as a life-saving cure – however overblown – has defined the necessary action.
The pandemic plan caused the government to buy lots of Tamiflu. A cynic might say that not using up a big stockpile with a finite shelf life when there is a use for it would be an affront to the tidy civil service mind, which has a horror of untidiness and leaving loose ends and which is driven by the need to prevent waste at all costs.
There is no doubt that Tamiflu brings benefits. The earlier it is given the greater they are. The ideal is to take it before the onset of symptoms. Even after a couple of days it shortens the illness by a day or so. It is less certain how effective it is in preventing the development of severe complications, although it is reasonable to assume that it may reduce their frequency. Its effect in reducing the transmission of the virus from person to person is probably not very great. Influenza virus sufferers are excreting virus before the onset of symptoms so taking Tamiflu a day or so later means that they will already have had plenty of opportunities to infect their close contacts.
So the benefits to be expected from giving Tamiflu – even on a grand scale – are real, but limited. And there are downsides. Some will experience side effects. These are well known. Nausea and vomiting has been taken up by the tabloids. In most of the anecdotes it is impossible to know whether the symptoms have been caused by the drug, or by the influenza for which the complainant was being treated.
The big worry is that the exuberant and poorly controlled use of Tamiflu will hasten the appearance and spread of resistant mutants. It used to be thought that these were feeble viruses that spread poorly. No longer. H1N1 seasonal viruses that are highly resistant and effective spreaders suddenly appeared throughout Europe in the 2007-2008 winter flu season. Only time will tell whether swine flu will go down the same road. As a general principle the use of a single antimicrobial agent sooner (if poorly controlled) or later (when under medical control) selects for resistance. Exceptions are few and far between. So the operations of the National Pandemic Influenza Service carry a big risk. The race is between resistance and the vaccine.
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