On 16 March, a needle was put in the arm of a Seattle woman who may change the world.
Jennifer Haller had a candidate vaccine against coronavirus injected into her bloodstream – the first human trial aimed at preventing the further spread of a disease that could still kill millions.
Jennifer Haller becomes the first person to receive a dose of a candidate COVID-19 vaccine
As her story hit the headlines, many celebrated: It appeared that perhaps Donald Trump had been right two weeks earlier when he said: "Very soon, we're going to come up with a vaccine."
Not so, says everyone who is involved in the most closely watched race since the one to reach the moon.

Developing a successful vaccine is complex, painstaking and difficult.
And it is expensive. The UK government, which has put in £250m so far, is just one of many administrations around the world spending billions.

But, while it will be too late for many of the people who have caught COVID-19 already, it is essential to help those who will need to remain free of the disease if they want to survive.

To get a vaccine to the people who need it, there are four main phases.
Vaccines have been used to prevent people catching viruses for hundreds of years.

During that time, the technology used to create them has become increasingly sophisticated.

To do so, researchers examine the qualities of the disease they are trying to prevent – often looking at the structure of the pathogen and how it operates inside the body – to work out how to boost the body's defences against it.
Laboratories around the world will already have been working on vaccines to prevent coronaviruses before SARS-CoV-2, the one that causes COVID-19, was identified in China in January.
Like COVID-19, the coronavirus MERS was linked to animal-human transmission - from camels.

Two serious outbreaks of coronaviruses, MERS and SARS, occurred in the last 20 years, reinforcing the need for potential vaccines.

Vaccines were worked on for those two diseases, but what prevented them being brought forward was that the outbreaks were brought largely under control. Drug companies had little incentive to continue pressing on as they could not get the money back on their investments.

SARS-CoV-2 is different to MERS and SARS, and will need a different vaccine.
But some of those working on a solution have quickly been able to identify candidates they believe could be successful.
One of those is Moderna, the company whose vaccine candidate was injected into Jennifer Haller's arm as part of the first human trial.
Others have been working frantically to advance research that was in an early stage, bringing forward other potentials in case they too might work.

All, some or none of these could end up being successful.

The Coalition for Epidemic Preparedness Innovations, or CEPI for short, is an international coalition that has been set up precisely to tackle outbreaks such as coronavirus, by developing new vaccines.
But it is in its infancy - having been set up just three years ago - and those in charge say it would have benefited from several more years of operation if it was to be considered 'ready'.
Nevertheless, CEPI is trying to lead the effort to save millions of lives around the world and says it needs $2bn (£1.61bn) to do so.

It is just one of a number of organisations and countries trying to find a vaccine. The race is on to see which one can find the drug that will prevent people developing COVID-19.

When CEPI put out a call for proposals, it had 48 applications for funding from people proposing a candidate vaccine. This has been whittled down to eight.

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