Critical patients need swine flu drug boost

The World Health Organisation on Wednesday recommended boosted antiviral treatment for hospital patients with severely weakened immune systems who contract swine flu, following recent clusters of Tamiflu resistance.
Although the WHO said there was no evidence that the two clusters found in Wales and in North Carolina marked a wider public health threat, it reiterated calls for vigilance and modified treatment advice for the frontline flu drug.
In the two clusters found in single hospital wards in October and November, patients -- eight in Wales and four in the United States -- were suspected of infecting each other with the Tamiflu-resistant strain.
In such patients with suppressed immune systems, "standard treatment doses and duration for treatment with oseltamivir (Tamiflu) are unlikely to be sufficient," the WHO said in a briefing note posted on its website.
"Though clinical judgement is important, doses may need to be increased and continued, without interruption, for the duration of acute illness," it added.
The UN health agency also recommended that the alternative drug to Tamiflu, Zanamivir, "should be considered as the treatment of choice for patients who develop prolonged influenza illness despite treatment with oseltamivir."
Oseltamivir is sold by pharmaceutical company Novartis under the brand name Tamiflu, while GlaxoSmithKline's Zanamivir is marketed as Relenza.
The WHO repeated the need for "vigilant monitoring" of the Tamiflu-resistant flu virus. "Experience with seasonal influenza viruses shows that resistant viruses can quickly spread within the general population and become established, rendering one or more antiviral drugs ineffective," it cautioned.
Within the past two weeks, the number of documented cases of Tamiflu resistance in those who have contracted A (H1N1) flu has risen from 57 to 96, according to the global health watchdog.
About one third occurred in patients whose immune systems were severely weakened by blood problems, aggressive chemotherapy for cancer, or post-transplant treatment.
There was no sign in the US and British clusters of infection that the resistant strain had infected hospital staff, other wards or outside. "Results to date are reassuring," the WHO said.
"Although all incidents of oseltamivir resistance merit investigation, no evidence suggests that events to date constitute a public health threat."