GENEVA (Reuters) - The World Health Organization will convene its emergency committee later this month to examine whether the H1N1 flu pandemic has peaked, its top influenza expert said on Thursday.

What we are hoping for is that the worst is behind us, Keiji Fukuda told a news conference.

Fukuda said the committee, which makes recommendations on the state of a pandemic to WHO Director-General Margaret Chan, would decide whether the H1N1 pandemic declared in June had entered a post-peak or transition phase.

Designating a transition phase in this way -- indicating that the pandemic is continuing but the overall trend is back toward seasonal patterns of influenza -- would help national health authorities look to the future, he said.

Even if the WHO decided the pandemic had peaked, the virus remained active, causing disease and death, and could continue to flare up in some regions, as it had done recently in West Africa, Fukuda said

The ending of a pandemic cannot be construed an abrupt on-or-off situation, he said.

Laboratory-confirmed deaths total more than 15,000, but the real toll is likely to be much higher, although that will not be established for a year or two, he said.

The WHO has not yet set a firm date for the emergency committee meeting, but it would probably be in the last week of February, Fukuda said.

Another group of influenza experts will meet next week to make recommendations on the composition of the flu vaccine for the next northern hemisphere influenza season, he said.

The recommendations will be published on February 18.

Fukuda noted that H1N1 remained the most dominant influenza virus, so it was possible that it would be included in the next seasonal jab.

(Additional reporting by Kate Kelland in London)

(Reporting by Jonathan Lynn; Editing by Stephanie Nebehay)