It's on everyone's Christmas list - a Covid-19 vaccine this side of New Year.
While the government is working to that timeline even the head of its own Vaccines Taskforce thinks that it's very far from certain.
And while UK-based companies are increasingly confident they can make the millions of doses we need here in the UK, given stages of development for the different vaccines, it's also likely we'll be relying on contracts for vaccines made overseas.
"We've seen a lot of data with encouraging signs for immune response that we hope will translate into protection against infection," according to Kate Bingham, Chair of the UK Vaccines Task force.
"But until we finish the studies we don't know what protection those vaccines will give.
In the race to develop a vaccine then, these are the runners and riders:
Oxford University/Astra Zeneca - by far the most well known in the UK, the Oxford vaccine will rely on a harmless Chimpanzee virus to carry the Covid antigen into our bodies. It's one of the most well advanced in clinical trials and manufacturing of millions of doses of the vaccine has already begun in the UK.
The government has ordered 100 million doses.
BioNTech/Pfizer - A collaboration between US drug giant Pfizer and a German biotech firm, this vaccine is based on a sequence of the Covid virus' genetic code. A sequence of its mRNA that has shown promising results in human trials. Like the Oxford vaccine in it's in the final "stage three" human trials. The company said it could know whether its vaccine works as soon as this month.
The government has ordered 30 million doses.
Janssen (Johnson & Johnson) - Another vaccine that relies on a virus (this time a harmless human one) to ferry the Covid antigen into our cells. This vaccine just entered phase three trials last month.
The government has ordered 30 million doses.
Novavax - Has been developed by an American biotech company. It's based on protein molecules, synthetic pieces of the coronavirus stuck to microscopic particles. It has just entered phase three trials (including one here in the UK).
A factory in Teeside will also be making the 60 million doses ordered by the UK government.
The UK government has also ordered 60 million doses each from GSK/Sanofi and French firm Valneva but neither product is as advanced as those above.
So far, the Oxford/AZ and BioNTech vaccines are out in front.
Given the urgency of the pandemic, both companies involved are already manufacturing doses of the vaccine even though they won't know if they're successful until trials are complete.
But even once the trials are over, there's the crucial independent safety assessment by regulators.
"We have to receive positive data but regulators have to approve that they think this is safe and positive," says Ms Bingham.
"We don't know how long that step will take - our goal is to have a manufactured vaccine ready for when they say 'yes you're ready to go'."
But it's this regulatory delay which could push a vaccine that's physically "ready" by Christmas into not being deployed until next year.
And it's at that point that other vaccines, slightly behind in the race might step in.
The Novavax vaccine has only just begun phase three trials, but it's a type of vaccine that has been used safely in millions of people already. One that regulators are familiar with.
The two front-runners in the Covid race based on viruses and mRNA are far less well studied and between them might require much more rigorous review.
But if we do find ourselves waiting for these vaccines, it could be quite some time.
Teeside-based Fujifilm is preparing to start making the Novavax vaccine.
But its manager told us they don't expect to be producing "significant volumes" until the second half of next year.
Then there's the other issue of how many doses we're actually going to need.
If the plan, as the government insists, is to vaccinate the whole UK population, it's very unlikely that the task can be complete next year.
Partly because it relies on more than one of the six candidates being ready by their very earliest timeline, but also because many of the vaccines are likely to require more than one dose to be effective.
But the plan the government's vaccine taskforce is working on is that only the most vulnerable and the elderly will be given the vaccine, at least in the first phase of any vaccination campaign.
And because many of the vaccines might need two doses, they're planning on using one of the vaccines that finishes the race slower could be used to "boost" the effects of the first vaccine with a second dose.
It's also emerged that the UK has deliberately avoided sourcing vaccines manufacturer in the US.
While task force boss Kate Bingham wouldn't say why, the implication is that the posturing by the current US administration about reserving medicines and vaccines for "America first" means that contracts with US companies exporting vaccine from the US might not secure.
Put it all together and while we may have a vaccine by this Christmas, it's not that likely that any of us get jabbed by then.
And for those of us under 50 or without pre-existing Covid risk factors it's unlikely we'll get the vaccine next year at all.
For that reason, it's also likely that for some time after a vaccine is available, certain restrictions on our freedoms will continue.
It might be the only way of ensuring the vulnerable waiting for a vaccine, or waiting for their vaccine "boost" will be safe.
Leading some experts to urge the government to be clearer with the British public about what they can expect, when, from a vaccine.
"The time has come to start painting a picture of what 2021 might look like, in a grown -up way," says Professor Nilay Shah, from Imperial College London.
"I think people are willing to hear that and understand that it will take time".