Swine flu has not mutated into more serious disease: WHO

The number of swine flu cases is expected to rise as the Northern Hemisphere moves into winter, WHO Director-General Margaret Chan said at the opening ceremony of the organisation's annual Western Pacific meeting in Hong Kong.

"The virus can mutate any time. But from April to now, we can see from the data given to us by laboratories worldwide that the virus is still very similar (to the previous state)," Chan told reporters.

She said that the vaccines produced so far have been very effective but that the biggest challenge in combating the pandemic would be ensuring enough vaccines got to the world's poorest countries.

China has already begun to vaccinate people with its own domestically produced vaccine, authorities there and Chan said.

Ideally, three billion doses could be produced worldwide annually, enough to cover almost half the world's population, she said.

Her comments come after the WHO warned last week that the annual production of swine flu vaccines is expected to fall well short of the 4.9 billion doses that it had earlier forecast.

From now till the end of the year there would be "a limited supply" but the situation would ease in the first quarter of next year, Chan said.

"Results of early clinical trials suggest that a single dose of pandemic vaccine will be sufficient. If confirmed, this finding will literally double the amount of vaccine available," Chan said.

"Here's the big question: Will this result in more equitable distribution of vaccines? Let me assure you: I am pursuing this opportunity from several angles."

The WHO is working with the United Nations on raising a billion dollars to help buy vaccines for developing countries that cannot produce them themselves.

There are fears that poorer countries will not get enough vaccines despite a pledge last week by the United States and eight other nations to make 10 percent of their vaccine supply available to others in need.

The global swine flu, or influenza A(H1N1), death toll has reached 3,486, up 281 from a week ago, with the Americas region having the highest toll, according to the latest WHO figures.

Chan said that only high-risk patients such as the elderly, the obese and those with underlying illnesses would be severely affected by the disease.

But she warned that the death of pregnant women in the developing world during a pandemic would be "especially tragic" because the number could be much higher than elsewhere.

In the Western Pacific there are about a million people living in poor conditions without access to healthcare, making them particularly vulnerable to infection, WHO regional head Shin Young-soo told reporters Sunday.

Developing countries are not only unable to produce the vaccine for the virus but their people are more vulnerable to infection because of poverty, crowded living conditions and lack of healthcare, according to the WHO.

Chan said another concern was side effects from the vaccine and that the WHO was working with governments to put in place a system for closely monitoring post-vaccination.

She said Hong Kong, where there is extra concern about the virus because of the city's experience with Severe Acute Respiratory Syndrome (SARS) in 2003, could relax its measures against a swine flu outbreak "step-by-step".

She advised it to focus long-term resources on saving patients and reducing the number of serious cases.

Chan managed Hong Kong's response to avian influenza and SARS during her nine-year stint as Hong Kong's director of health.

(c) 2009 AFP