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by Marijana Domazet, Monday, March 25, 2013 | Categories: Influenza | Tamiflu

Although the most notable outbreak of the swine-flu peaked in 2009, the reports regarding the virus and its treatment have continued to make headlines in mainstream media. A few days ago, researchers in Australia presented findings that indicated that a cluster of virus samples showed that it was resistant to oseltamivir in around 10% of cases in New South Wales. Oseltamivir is the active ingredient in Tamiflu.

These findings were presented at the Annual Scientific Meeting of the Australasian Society for Infectious Diseases. The emergence of this resistant strain of this virus, which is called H1N1pdm09, gave rise to several concerns among public health experts. The first concern came from the fact that this virus was found in the community, rather than with sick patients who had pre-existing conditions, which resulted in a weak immune system. This implied that the concern for the spread of the virus would not only be for particularly vulnerable patients, but also for healthy individuals. The second concern came from the fact that the H1N1pdm09 had spread to individuals who had never been treated with Tamiflu. This indicated that the virus could spread quite effectively from one person to another even if there is an oseltamivir intervention. The final concern, which was never stated by researchers, but has been noted in mainstream media, was the controversy regarding the efficacy of Tamiflu that had been reported in the last 12 months.

We were not surprised to read about a treatment resistant virus developing, as it has happened in the past with other diseases and treatments. Adamanatane was used to treat influenza but this is now largely obsolete for this purpose following a development of resistance. However, we were surprised to see that not all the reports had put the findings into context. The Australian researchers reported that they had found this to affect two per cent of their study sample, and a total of eight resistant cases were confirmed in the UK to date. Naturally it could be argued that these numbers are concerning, however they are far from alarming. Similarly, while it is important not to underestimate a new resistant strain of the virus, this strain is just one of many viruses that are circulating. This is in stark contrast to how it was when the swine flu was the dominant virus in 2009. Perhaps the most encouraging news was the fact that although H1N1pdm09 appears to be resistant to oseltamivir, other reports suggested that the same virus might be sensitive to zanamivir (which is the active ingredient in Relenza). Relenza operates in a different way from Tamiflu (even although it also disables the influenza virus through neuraminidase inhibition).

We feel that once these findings have been put into context, they show a more realistic version of the implications of this new virus. The importance of monitoring the spread of new viruses and strains of viruses is understandable, but our interpretation of the findings to date suggests that it is too early to be alarmed by these reports. The really scary flu virus is H5N1. If that started to pass from human to human in meaningful numbers then we may have a very serious problem.

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