The US is within a few weeks of commencing the most ambitious crash inoculation programme in world history.
|The US government has launched a massive public relations campaign which raises awareness of the H1N1 virus and encourages everyone to be inoculated [GALLO/GETTY]
Given worst-case projections that half the US population could become infected with the H1N1 virus this year, the government is determined to become the global pace-setter by assuring that as many Americans as possible are vaccinated before the pandemic can become a mass killer.
This week, the Federal Drug Administration approved commercial production by four vaccine manufacturers, even before clinical trials of the drug have been completed for young children and pregnant women, two particularly vulnerable groups.
But US authorities had already locked up advanced purchase of about 600 million doses of the vaccine.
Because the initial trials show just a single dose to be highly effective, the US may need only half that amount to inoculate its entire population.
By contrast, Chinese authorities have committed to producing enough vaccine for only five percent of the country's much larger population.
The US and eight other counties have notified the World Health Organisation (WHO) that the remainder of its surplus vaccine supply could be made available to countries in need.
Ten hospitals around the US have conducted the clinical trials on some four thousand volunteers, from six-month old babies to people over the age of 70.
They are paid only a few hundred dollars a piece to become "guinea pigs" - a term the medical researchers say they avoid using when referring to the vaccine trial subjects.
But money is rarely why volunteers enter the program.
Retired nurse Betty Ruano was motivated by a sense of civic duty together with a grim personal awareness.
|The US inoculation programme rolls out beginning in October [AFP]
She said: "My dad's parents died in the flu epidemic of 1918," the global killer which originated on American soil and is estimated to have been the most lethal in history.
"And so I've been tuned into the risks of flu."
If all goes as planned, the first of 145 million doses will be ready for distribution by early October.
The first 3.4 million doses will come in the form of nose spray.
Immunising nearly all the US population before the peak flu season ends could cost the government up to $9 billion.
It will be given out free to doctor's offices, retail pharmacies and local health departments.
But not enough vaccine may be produced in time for the peak of the season, partly because manufacturers are still racing to meet the demand for seasonal flu vaccine.
While the vaccinations are voluntary, Barack Obama, the US president, has led the government's high-profile public relations campaign urging everyone to be injected.
Not only is the vaccine campaign a public health challenge, but it also carries some political risk at a time when Obama is also fighting against formidable odds to enact healthcare coverage for the 15 per cent of the population which lack medical insurance.
His commitment comes three decades after one of his predecessors, Gerald Ford, pursued a crash flu vaccination programme that treated 46 million Americans.
It was a pandemic, though, which never materialised.
Dozens of people, however, suffered fatal autoimmune reactions to that vaccine, while hundreds more were permanently maimed by side effects.
Ford was accused of exaggerating the threat, a contributing factor in his losing the 1976 presidential election.
This time, though, experts believe the evidence of a major pandemic is much more alarming.
The government has been airing TV messages featuring parents whose children died from milder strains of flu.
On camera, one tearful mother says:
"The flu has changed our lives. It took one of our children. I could have gotten Emily a flu shot. I should have given all of our children a flu shot."
Yet authorities must deal with stubborn pockets of resistance to mass inoculation.
Some medical sceptics insist that vaccines, which employ weakened strains of the virus to generate antibodies against the disease, are just too risky.
And others suspect a political conspiracy afoot.
One conservative magazine expressed doubt that H1N1 even constitutes a pandemic, as the WHO has determined.
"The National Guard is even practising mock takeovers of public schools in the event of an ‘H1N1 riot.' What kind of riot could arise out of a flu that has only killed 1,000 worldwide," wrote the author of an article in "The American Thinker."
"Could a form of martial law be imminent? Obama appears ready to cross the Rubicon, and all he needs is a killer virus."