WASHINGTON (Reuters) - Drug makers are gearing up to make vaccines against the new H1N1 virus, starting test batches and pledging free doses for poor countries.
Governments are pledging billions for the vaccine -- the United States has set aside $1 billion, the Netherlands ordered 34 million doses and Australia has ordered 10 million doses as the World Health Organization declared a pandemic.
Yet no one is sure yet whether even to give the vaccine to anyone and if so, who should get it.
Usually the guidelines for influenza vaccination are clear -- give it to the oldest, the youngest and the sickest. In an average year, influenza is a factor in 250,000 to 500,000 deaths, and in developed countries, 90 percent are the elderly.
"The fact that we are seeing ongoing transmission now indicates that we are seeing something different," Dr. Daniel Jernigan of the U.S. Centers for Disease Control and Prevention told reporters this week.
Most cases are in people aged 5 to 24 -- usually the last group to get seriously ill from flu and the last group vaccinated during a normal flu season.
There have been few serious H1N1 cases among the elderly, perhaps because they have some pre-existing immunity to a similar H1N1 that circulated in the past, or maybe because their immune system response is different -- flu experts do not know yet.
To decide what to do, WHO officials will have to watch and see what this new strain does.