UK's COVID-19 study aims to vaccinate more than 10,000

British researchers testing an experimental vaccine against the new coronavirus are moving into advanced studies and aim to immunize more than 10,000 people to determine if the shot works.

Last month, scientists at Oxford University began immunizing more than 1,000 volunteers with their vaccine candidate in a preliminary trial designed to test the shot's safety. On Friday, the scientists announced they now aim to vaccinate 10,260 people across Britain, including older people and children.

The clinical studies are progressing very well and we are now initiating studies to evaluate how well the vaccine induces immune responses in older adults and to test whether it can provide protection in the wider population, said Andrew Pollard, head of the Oxford Vaccine Group.

Earlier this week, drugmaker AstraZeneca said it had secured its first agreements for 400 million doses of the Oxford-developed vaccine, bolstered by a $1 billion investment from a U.S. government agency, for the development, production and delivery of the vaccine, starting in the fall.

About a dozen different experimental vaccines are in early stages of human testing or poised to start, mostly in China, the U.S. and Europe, with dozens more in earlier stages of development.

Scientists have never created vaccines from scratch this fast and it's far from clear that any of the candidates will ultimately prove safe and effective. Often, possible vaccines that look promising early fail after testing expands to thousands of people one reason the crowded field is important.

Many of the candidates work in different ways, and are made with different technologies, increasing the odds that at least one approach might succeed.

Most of the vaccines in the pipeline aim to train the immune system to recognise the spiky protein that studs the new coronavirus' outer surface, so it's primed to attack if the real infection comes along.

The Oxford vaccine uses a harmless virus a chimpanzee cold virus, engineered so it can't spread to carry the spike protein into the body. A Chinese company created a similar shot.

Other leading vaccine candidates, including one from the U.S. National Institutes of Health and Moderna Inc. and another by Inovio Pharmaceuticals, simply inject a piece of the coronavirus genetic code that instructs the body itself to produce spike protein that primes the immune system.

Meanwhile, companies and governments are beginning to scale up production now, aiming for hundreds of millions of doses of the candidates they think might win the vaccine race.

It's a huge gamble that could waste a lot of money if their choices fail and must be thrown away but if they get lucky and a stockpiled vaccine pans out, it could help mass vaccinations start a few months faster.