WRAPUP 1-Companies could vaccinate 4.9 bln against H1N1 -WHO

* Vaccine makers pledge to work on swine flu if needed

* WHO works to secure doses for poor countries

* U.S. officials worry about drug resistance

By Katie Reid and Laura MacInnis

GENEVA, May 19 (Reuters) - Companies could potentially turn out 4.9 billion doses of vaccine against the new H1N1 influenza strain within a year under the best-case scenario, World Health Organization officials said on Tuesday.

WHO Director-General Dr. Margaret Chan told reporters after a meeting with 30 pharmaceutical companies that WHO was working to secure supplies of vaccine for poor countries in case of a pandemic. [nLJ556980]

U.S. health officials said they were finding higher-than-expected numbers of cases of seasonal influenza still circulating and worried that a drug-resistant strain may mix with the new H1N1 swine flu strain to create a dangerous new strain.

United Nations Secretary-General Ban Ki-moon said it was essential for drugmakers to work with governments to avert the worst potential impacts of the new H1N1 strain, which has killed 81 people and been confirmed in nearly 10,000 globally.

"Partnerships with the private sector are absolutely vital," Ban told representatives of the WHO's 193 member governments gathered in Geneva, urging them to think beyond their borders in their response to the H1N1 strain.

Six companies have pledged to make 10 percent of the vaccine they produce available for distribution to poor countries, and eight are in talks about donations, said Gelmer Leibbrandt, general manager of Schering-Plough's SGP.N vaccine unit Nobilon.

Chan said that vaccine makers have shown a very serious commitment to help the international community prepare for a pandemic of flu, which, while seemingly mild so far, could become more severe as it circles the globe.

VACCINE QUESTIONS

Questions remain about whether an H1N1-only vaccine is needed in the near term -- especially if its production cuts the world's supply of immunizations for seasonal flu, which is involved in the deaths of up to 500,000 people a year and causes severe illness in millions.

U.S. Health and Human Services Secretary Kathleen Sebelius said pharmaceutical companies should ramp up their production of seasonal flu vaccine and then later switch to pandemic injection making if necessary.

"There is still so much uncertainty about this virus that it is really premature for us to even make a determination about how many people would appropriately be vaccinated, in what order, how many doses will be required, at what point. All those discussions are still very much under way," Sebelius said.

WHO said companies plan to produce approximately 480 million doses of seasonal vaccine in 2009 -- each one containing three separate vaccines against the three most common circulating flu strains.