FACTBOX: Japan's plans to tackle spread of H1N1 flu

(Reuters) - Japan said this week the new H1N1 influenza virus has reached epidemic proportions in the country, but it is still lagging in vaccine production.

The new virus, which emerged in March, has been declared an international pandemic and the World Health Organization predicts a third of the global population will eventually become infected.

Although most cases are mild to moderate, H1N1 appears to be about as deadly as the more common seasonal flu, which kills some 10,000 people a year in Japan and up to 500,000 globally.

Following are key facts about the new flu in Japan, which could become one of the first challenges for the winners of an August 30 national election.

SPREAD OF H1N1 FLU

-- Japan had confirmed some 5,000 cases of the H1N1 flu as of late July, when it changed its method of tracking the outbreak. Three have died so far, with the first fatality confirmed last Saturday.

-- The government now monitors group contagion and hospitalized cases. In the week of August 12-18, 86 patients were hospitalized because of the H1N1 flu, with more than 70 percent of them aged below 20.

-- Japan's National Institute of Infectious Diseases said on Friday that the new flu has reached epidemic proportions in Japan after the number of flu patients reported by about 5,000 core medical institutions rose above 1.00 per facility, which is Japan's yardstick for the start of a flu epidemic. The benchmark often rises above 1.00 with seasonal flu.

-- Japan last month confirmed its first case of a genetic mutation of the H1N1 flu virus that shows resistance to antiviral flu drug, Tamiflu, made by Switzerland's Roche AG. But the two main antiviral drugs, Tamiflu and GlaxoSmithkline's Relenza, have helped most patients.

-- With the flu spreading at a faster rate than expected in the summer, Japan wants to delay the spread before the autumn weather sets in, worsening the situation. But it has warned that the new flu could spread more quickly once students return to school after summer holidays in September.

VACCINE

-- Japan wants to be ready to provide enough H1N1 flu vaccine to treat 53 million people, nearly half the country's population. But Japanese makers, which are allocating some resources away from the production of vaccines for seasonal flu, are only expected to be able to produce enough vaccine to treat 13-17 million people, far fewer than they had originally targeted. The government is considering importing vaccine to fill the gap, although some analysts said Japan should also provide vaccine to developing countries to help the poor with the disease.

-- The H1N1 flu vaccine is expected to be ready for mass vaccinations around the end of October, although the government has not yet prioritized who will be vaccinated first. A panel of experts is meeting this month to discuss this and other issues such as possible side effects of the vaccine. The government will make a final decision taking into account the panel's recommendations.

-- There are four makers that produce both seasonal and H1N1 flu vaccines for the Japanese market: Denka Seiken Co., Ltd, the Research Foundation for Microbial Diseases of Osaka University, Kaketsuken (The Chemo-Sero-Therapeutic Research Institute) and the Kitasato Institute.

OTHER STEPS

-- The government has urged the public to wash their hands and gargle. It has also said that those with flu symptoms should wear masks and avoid going outside, but there are no plans to limit public gatherings.

-- The government is stockpiling antiviral drugs and planning to distribute a list of serious cases of the disease to medical institutions.

(Reporting by Yoko Nishikawa; Editing by Joseph Radford)