GENEVA (Reuters) - Two or three years' hard work are still needed to ensure the world can cope with a pandemic that could affect millions of people, U.N. bird flu coordinator David Nabarro said on Wednesday.

Nabarro said countries had to prepare for the risk of millions of people being infected by a disease such as influenza, and for the knock-on effects it would have on the economy.

Most countries had pandemic plans but only a few were prepared to deal with the mass absenteeism that could arise.

"We need hard work for at least two or three years more to make sure that the whole world is properly pandemic-ready," he told a news conference.

It was particularly hard for poor countries to find the resources to prepare for such a potential disaster.

India is hosting a meeting of health and agriculture ministers in New Delhi between December 4 and 6 to review global preparedness, based on studies of 146 countries, he said.

Scientists believe a flu pandemic is only a matter of time, and a mutation of the deadly H5N1 strain of the bird flu virus could be the trigger.

Contact with sick birds is the most common way for humans to contract H5N1, which has been fatal in 204 of the 332 cases since 2003. A few cases of human-to-human transmission have been recorded.

If the virus develops a way of transmitting easily among humans, the results could be devastating.

It could take between four and six months to produce a vaccine that can counter the new strain of the virus, and in that time the first wave of the pandemic would spread around the world, possibly causing many deaths.

RAPID RESPONSE

Nabarro said a flu outbreak would need a rapid response within days to isolate it and deal with the consequences. Plans also required countries to stockpile Tamiflu, the anti-viral drug produced by Roche Holding, which is effective in treating the current strain of bird flu.

They could include stockpiling a vaccine against H5N1 in case the virus causing a pandemic could be neutralised by an anti-H5N1 vaccine - which might not be the case.

More important than any medical tools was the ability to isolate healthy people from those carrying the disease - known as "social distancing", Nabarro said.

This would include controlling the way people congregate together and providing protective equipment such as masks.

Current efforts to mitigate the economic effects of an outbreak are focusing on the financial sector - making sure automatic cash dispensers have cash and banks can settle payments. They also look at ways of ensuring transport is not disrupted unnecessarily and essential services are kept going.

Nabarro said that, in the past two years, countries had become more open about reporting outbreaks of bird flu among poultry and human cases of H5N1.

The disease remained entrenched in poultry in Indonesia, which had suffered more fatalities than any other country, but Jakarta had been open about reporting even suspected cases to the international community, he said.

However, senior WHO official Paul Gully said Indonesia still did not cooperate fully with the World Health Organisation (WHO) on sharing virus samples since it said these were being passed on to drug companies without its permission.

Gully told the briefing that the WHO was continuing to negotiate with Indonesia, which feared the samples might be used to produce vaccines that poor countries could not afford.