The head of a key panel advising the UN health agency on the swine flu pandemic said Wednesday there was no reason to wind down the alert before an expected second wave in the southern hemisphere.
Australian disease expert John Mackenzie, chairman of the World Health Organisation's Emergency Committee, told an international inquiry that he was waiting to see the progress of A(H1N1) influenza in the south's traditional autumn and winter flu seasons over the coming months.
"We do have some concern," he said in response to questions.
The Emergency Committee of scientists played a crucial role in recommending an international emergency over the new virus and whether or not a pandemic should be declared.
"I don't think that we will terminate at any stage yet the public health emergency," Mackenzie said, underlining that he did not feel a pandemic could be declared over "until we see how it progresses in the southern hemisphere."
"Until we're certain, we can't lower our guard."
The inquiry panel set up by the WHO started this week to probe the international response to swine flu since it was uncovered in the United States and Mexico nearly a year ago.
Its questions were prompted by evidence that A(H1N1) flu has died down with the end of the flu season in the northern hemisphere, as well as doubts about its severity in terms of death and illness.
However Mackenzie said the virus was "certainly as severe" as those that sparked flu pandemics in 1957 and 1968, with the unusual characteristic of being more dangerous for young people and pregnant women rather than the elderly.
"This is quite crucial in our understanding of what severity is," he added.
He also pointed out that previous pandemics had sometimes been more severe during their second or third wave, and that A(H1N1) was still active in West Africa and parts of Asia.
The Emergency Committee is a highly confidential body and Mackenzie's testimony shed unprecedented light on decision-making on the pandemic since April 24, 2009.
Mackenzie, a professor of tropical infectious diseases at Curtin University in Perth, is also a member of the 29-strong review panel assessing the international response.Reuse content