One of the ongoing debates in the world of influenza has been over the efficacy of administering oseltamivir (Tamiflu) in the treatment of mild influenza in otherwise healthy individuals.
You may recall that last December a cluster of articles appeared in the BMJ which seriously questioned the lack of supportive scientific evidence in this matter (see BMJ: A Review Of Tamiflu’s Efficacy Against Seasonal Influenza).
Published 8 December 2009, doi:10.1136/bmj.b5106
Cite this as: BMJ 2009;339:b5106
While the entire study is worth reading, the bottom line was there is insufficient evidence, according to the authors, to conclude either for or against Tamiflu for use in healthy adults with seasonal influenza.
In other words, the authors stated that more studies were needed.
Although it certainly won’t end the debate, we’ve a new open access retrospective study appearing this week in the BMJ which suggests that administration of oseltamivir may have significantly reduced the incidence of pneumonia among otherwise healthy pandemic H1N1 patients.
BMJ 2010; 341:c4779 doi: 10.1136/bmj.c4779 (Published 28 September 2010)
Cite this as: BMJ 2010; 341:c4779
Effectiveness of oseltamivir on disease progression and viral RNA shedding in patients with mild pandemic 2009 influenza A H1N1: opportunistic retrospective study of medical charts in China
Conclusions Chinese patients with 2009 H1N1 infection predominantly presented with features of uncomplicated, self limiting acute respiratory illness. 2009 H1N1 might be shed longer than seasonal influenza virus.
Treatment with oseltamivir was associated with a significantly reduced development of radiographically confirmed pneumonia and a shorter duration of fever and viral RNA shedding.
Though these patients benefited from treatment, the findings should be interpreted with caution as the study was retrospective and not all patients underwent chest radiography.
For those who would like the short version, there is a press release covering the highlights. I’ve excerpted a few paragraphs. Follow the link to read it in its entirety.
Research: Effectiveness of oseltamivir on disease progression and viral RNA shedding in patients with mild pandemic 2009 influenza A H1N1: opportunistic retrospective study of medical charts in China
Healthy people who caught swine flu during the 2009 pandemic may have been protected against developing radiographically (x-ray) confirmed pneumonia by taking the antiviral drug oseltamivir (Tamiflu), concludes a study of cases in China published on bmj.com today.
The researchers also show that oseltamivir treatment was associated with shorter duration of fever and viral RNA shedding (the period when a virus is contagious), although they stress that their findings should be interpreted with caution.
While the lack of peer-reviewed RCTs (Randomized Controlled Trials) on oseltamivir – which can provide genuine ethical dilemmas to mount – will continue to leave some questioning the efficacy of Tamiflu in mild influenza, anecdotal reports and retrospective analysis continues to show the drug to be beneficial, particularly in cases of severe influenza.
Today’s study adds a new dimension to the debate, by strongly suggesting that it may reduce morbidity in healthy adults with mild influenza symptoms.
Additionally, the researchers reported that:
Our study suggests that 2009 H1N1 is shed from one day before the onset of symptoms to eight days after onset for most (91%) patients and can be shed up to 21 days.
The BMJ’s summary reads, in part:
What this study adds
In patients with mild pandemic 2009 H1N1 infection, oseltamivir can protect against subsequent development of radiographic pneumonia, even in those who start treatment more than two days after the onset of symptoms
Early oseltamivir treatment within two days of symptom onset can reduce the duration of fever and viral RNA shedding
Pandemic 2009 H1N1 virus is shed from one day before the onset of clinical symptoms to up to eight days after onset for most patients and is shed for longer than seasonal influenza virus
There are other concerns when it comes to the routine use of oseltamivir with mild influenza, including the possibility of causing side effects and the (potential, at least) of generating resistant strains of the influenza virus.
Both matters to be taken up by other studies and on another day.