National Councillor Doris Fiala receives a vaccination during a H1N1 swine flu virus vaccination session for members of the national parliament, during the winter parliament session in Bern, November 24, 2009. Credit: REUTERS/Michael Buholzer

H1N1 swine flu has not peaked yet but seems to be waning in Canada and the United States, signaling that the end of the pandemic may be on the horizon, the World Health Organization (WHO) said on Thursday.

A third wave of infections may still be ahead, Keiji Fukuda, the WHO's top flu expert, said. But he added there was no sign of widespread resistance to Tamiflu, the main drug used to treat the H1N1 flu strain.

I think it's fair to say that we still haven't fully gotten through the pandemic and that it is possible that there could be unexpected events which occur, Fukuda told a news conference.

It is quite possible to have a pandemic on the milder side. And if we are experiencing that and the number of serious cases is kept down, then it is something again for which we should all be thankful, he said.

H1N1, which emerged in March, causes moderate symptoms in most patients but poses greater risks to pregnant woman, young people and patients with underlying health problems, according to the WHO.

The United Nations agency declared a full-blown pandemic -- at six on its six-point scale -- under way on June 11. The flu strain has caused at least 7,826 deaths worldwide as of November 27.

New flu strains which spark pandemics typically cause large outbreaks and then go through a transition period when the virus essentially becomes the seasonal influenza virus, Fukuda said.

The WHO and its advisory committees are gathering scientific data to assess the possible end of the pandemic, Fukuda said, telling journalists: I anticipate that at least sometime in 2010 we will be discussing this in formal settings, in more concentrated ways.

Again, I think it's a little bit early to begin those discussions now because we are still in a period where some countries are still increasing in terms of infections, even though in some countries, such as the United States and Canada, it looks like infections and cases are going down, he said.


Tamiflu, made by Swiss drugmaker Roche and known generically as oseltamivir, remains the frontline antiviral against H1N1, though the WHO is aware of 96 cases of resistance to the drug, according to Fukuda.

We do not see widespread resistance to oseltamivir anywhere, he said.

Tamiflu-resistant H1N1 viruses have not spread to hospital staff or beyond despite spreading among two clusters of patients in Britain and the United States, the WHO said in a statement issued overnight.

A dozen patients in Wales and North Carolina, all with severely weakened immune systems because of underlying health conditions, were infected with Tamiflu-resistant H1N1 in October and November.

The Netherlands reported its first death on Thursday of a patient suffering from a drug-resistant strain of H1N1. The government health agency said he had been treated with Tamiflu but had developed resistance to the drug.

Patients with severely compromised immune systems are highly susceptible to infection, particularly difficult to treat and especially likely to develop resistance, WHO said.

Zanamivir should be considered as the treatment of choice for patients who develop prolonged influenza illness despite treatment with oseltamivir, it said.

GlaxoSmithKline and Biota make zanamivir under the brand name of Relenza, a flu drug that is inhaled.

The WHO addressed concerns voiced in some media that ties with the pharmaceutical industry among experts on the organization's advisory bodies may influence policy decisions, especially those relating to the influenza pandemic.

It dismissed the suggestions, declaring that numerous safeguards were in place to address any possible conflicts of interest in experts serving on its advisory panels.

Allegations of undeclared conflicts of interest are taken very seriously by WHO and are immediately investigated.