UK experts are questioning the use of antiviral neuraminidase inhibitors to treat seasonal or pandemic outbreaks of flu, and say carrying out randomised clinical trials to find definitive answers on this should be a “high priority” for the National Health Service.

The UK government has been fast stock-piling Roche's Tamiflu (oseltamivir) and GlaxoSmithKline's Relenza (zanamivir) since the H1N1 (swine flu) pandemic of 2009/10, as a key weapon in case of future large-scale flu outbreaks, but an expert steering group has stressed that there is little evidence on whether this is the best approach to treating a pandemic.

Their report, published by the Academy of Medical Sciences and the Wellcome Trust, argues that the failure to conduct trials during the 2009 H1N1 pandemic “has contributed to the current weaknesses in the evidence base”, and has fuelled recent controversies about the efficacy and effectiveness of neuraminidase inhibitors.

According to the review, antivirals can lead to a reduction in duration of symptoms by between 14 and 17 hours for seasonal flu, but unless the flu strain is particularly severe or the individual is very ill, “the benefits are unlikely to outweigh the risks of side-effects”. Nevertheless, the antivirals did significantly reduce deaths in hospitalised patients, particularly if they started treatment within 48 hours of first onset of symptoms, which could be critical in a flu epidemic situation.

The report supports the use of antivirals to treat patients who require hospitalisation, but also emphasises that decisions about widespread use in a new pandemic setting “must take into account factors such as the virulence of the circulating strain, cost-effectiveness, distribution and the risk of resistance”. 

The steering group concluded that carrying out randomised control trials of neuraminidase inhibitors use in hospitalised patients and in high-risk groups “is a high priority,” and that steps must be taken now “to put in place pre-agreed protocols and research infrastructure so that trials can begin as soon as a pandemic begins”.