The World Health Organisation received backing from member states Monday over its handling of the flu pandemic as WHO chief Margaret Chan said the world had been "lucky" with swine flu.
As the WHO's annual assembly opened here, French Health Minister Roselyne Bachelot bluntly dismissed criticism of the UN health agency as "unjust", calling some of it a "smear campaign".
Chan told representatives of the WHO's 193 member states that "good news" in public health terms was normally driven by political commitment, resources and the ability to deliver care.
"Sometimes, though, we are just plain lucky. This has been the case with the H1N1 influenza pandemic," she said.
"The virus did not mutate to a more lethal form," while the vaccine worked and it showed little resistance to anti-viral drugs, Chan added.
The WHO chief acknowledged that "a few health systems were overwhelmed and the effects were usually short-lived.
"Had things gone wrong in any of these areas, we would have a very different agenda before us today," she added.
Her comments came as France, the United States and India led public statements of support for the WHO's management of the pandemic.
Some health experts and politicians have criticised the WHO-led global effort against the 2009 H1N1 flu after the new virus was uncovered in Mexico and the United States in April last year, claiming there was an over-reaction.
Swine flu was declared a pandemic as it rapidly spread around the world, prompting massive spending on specially developed but largely unused swine flu vaccine and emergency precautions.
"While some have questioned some of the actions taken by the international community, the outcomes speak for themselves. I believe we made the right decisions at the right times," said US Secretary for Health Kathleen Sebelius.
India complimented Chan for her "untiring efforts" but the most trenchant support came from Bachelot, who made a point by point rebuttal of criticism levelled against the WHO and public authorities.
"I want to express, in France's name, our solidarity with the WHO, which has been taken to task in an unjust manner," she told the assembly.
Bachelot said knowledge about the severity of the virus was "imperfect" in the beginning yet decisive action had to be taken.
She also expressed concern about the perception of swine flu threat, especially for younger people, arguing that public thinking had been muddled and underestimated the risks.
"The vaccine, which was the answer to a real danger, turned into a source of risk in the collective mind," Bachelot said.
The French health minister also warned that doubts about expert advice and the role of the pharmaceutical industry could undermine future alerts.
"The effects of this smear campaign are potentially devastating," she said.
Pandemic flu has left 18,030 people dead since the virus was uncovered, according to the latest WHO data.
An independent committee of experts set up by the WHO is investigating the international response to the swine flu pandemic. It is due to deliver its findings by the beginning of next year.
Chan reiterated on Monday that she welcomed the review.
"We want to know what went wrong and, ideally, why. We want to know what can be done better and, ideally, how," she added.
The WHO assembly runs until Friday, and is due to examine an array of global health issues.