GENEVA – The two drugs used to treat the influenza should be used carefully and only when needed for the chronically ill, pregnant women and other vulnerable patients, global health officials said on Tuesday.

The new H1N1 swine flu appears to be a little more contagious and a little more severe than seasonal influenza but only patients who need them the most should get the drugs, in part to keep the drugs working well in case the swine flu becomes more dangerous, said Dr. Nikki Shindo of the World Health Organization.

Other health officials expressed worries that swine flu could mix with other viruses, including H5N1 bird flu, and become worse in the coming months.

We will recommend to consider the use of antivirals for high-risk groups or the group of people at increased risk, depending on the availability, Shindo told a news briefing.

The new virus has been confirmed in 5,251 patients in 30 countries, WHO said. Cases were reported around the world, with Colombia confirming six cases, and two cases each in Finland, Thailand and China.

The United States has the most, with 3,009 confirmed cases in 45 states, nearly 600 more probable cases and three deaths. Mexico has 58 confirmed deaths and Canada and Costa Rica each have confirmed one death from the infection.

The United States has only 116 hospitalized cases but Dr. Anne Schuchat of the U.S. Centers for Disease Control and Prevention said pregnant women appeared especially vulnerable to H1N1, just as they are to seasonal flu, and should get prompt treatment.

We have about 20 cases under investigation right now where the H1N1 virus has been found in association with pregnancy, Schuchat told reporters. Pregnant women risk dehydration and premature delivery when they have flu, she said.

ROCHE RAMPS UP PRODUCTION

Seasonal influenza kills up to 500,000 people in an average year but Shindo said that in Mexico, at least, the H1N1 flu was causing more severe disease. Despite this, she said most patients could recover from H1N1 with simple treatments such as hydration, and without any drugs.

Swiss drugmaker Roche AG, which makes Tamiflu under license from Gilead Sciences Inc., said it would donate 5.65 million packets to WHO to replenish stockpiles deployed against the H1N1 outbreak. Roche said it was ramping up production of the drug, known generically as oseltamivir.

Relenza, known generically as zanamivir, is the other drug recommended for use against H1N1 and is made by GlaxoSmithKline under license from Australia's Biota.

WHO has predicted the new H1N1 could eventually infect a third of the world's population.

The overall severity of a pandemic is further influenced by the tendency of pandemics to encircle the globe in at least two, sometimes three, waves, WHO said in a statement.

Schuchat said health officials were especially worried because seasonal flu viruses are still circulating and could mix with the new H1N1 strain, either in people or in pigs.

The working hypotheses for much of the influenza community right now is that this strain was circulating in pigs somewhere and eventually reassorted and was able to infect humans easier, Schuchat told reporters in a telephone briefing.

Unfortunately, reassortment happens. And this means that the viruses that we're seeing can exchange genetic material with other viruses that are circulating. This can happen in humans, in pigs, in birds.

BIRD FLU

Not only are seasonal flu strains circulating but also the H5N1 avian influenza virus, which has killed 258 out of 423 people infected since 2003.

... There are discussions going on about vaccine development and potentially manufacturing and even use, eventually, of an H1N1 virus vaccine, Schuchat added.

The CDC has deployed test kits for H1N1 to all 50 U.S. states and more than 70 countries. Quest Diagnostics Inc said it has developed the first commercially available test, as well.

Mexico declared its beach resorts were safe as it struggled to rescue its tourist industry from cancellations and billion-dollar losses.

Japan's women's soccer team dropped out of scheduled matches against the U.S. Women's National Team, citing H1N1 concerns.

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