A major breakthrough has been announced in the race for a Covid-19 vaccine, with the jab from Pfizer and BioNtech found to be more than 90% effective.
Here is everything you need to know about the coronavirus vaccine race.
What progress is being made with Covid-19 vaccines?
There are currently more than 200 coronavirus vaccine candidates being tested around the world.
About a dozen Covid-19 vaccines around the world are currently in the final stages of testing, but the one from German biotech firm BioNtech and US pharmaceutical company Pfizer is the first to report any results.
There are two frontrunners in the Covid-19 vaccine race - the one from Pfizer, called BNT162b2, and another being developed by the University of Oxford and AstraZeneca, which is also in phase three clinical trials.
Other potential vaccines in phase three trials include ones by US drugs firm Moderna and biotech company Novavax.
How promising are the results from the Pfizer/BioNTech vaccine?
They are interim findings, and studies are set to continue, but analysis shows that the vaccine can prevent more than 90% of people from getting Covid-19.
It has been tested on 43,500 people in six countries and no safety concerns have been raised.
The analysis was carried out after 94 confirmed cases of Covid-19 were found among those taking part in the trial.
The jab is known as a messenger RNA (mRNA) vaccine, which uses the virus's genetic code rather than any part of the virus itself.
It is injected into the body where it enters cells and tells them to create antigens.
When can we expect results from the Oxford vaccine?
More than 20,000 volunteers are now participating in trials for the Oxford vaccine, which are taking place in countries including the UK, South Africa, Brazil and Kenya.
Professor Andrew Pollard, head of Oxford's vaccine trial team, said he is optimistic data on safety and efficacy of their vaccine will be available by the end of the year.
Appearing before the UK's Commons Science and Technology Committee, he said there is a "small chance" of a vaccine being made available by Christmas.
The Oxford vaccine, called ChAdOx1 nCoV-19, uses a weakened version of a common cold virus (adenovirus) which causes infections in chimpanzees.
What other trials are ongoing?
As of mid-October, the World Health Organization had identified 42 "candidate vaccines" at the stage of clinical trials, up from 11 in mid-June.
Ten of them were at the most advanced phase 3 stage, in which a vaccine's effectiveness is tested on a large scale, generally tens of thousands of people across several continents.
Pharmaceutical companies Sanofi and GlaxoSmithKline have also teamed up with the hope of making a Covid-19 vaccine available by the middle of next year.
The Sanofi/GSK candidate is in the phase two stage, where the vaccine is being given to hundreds of people so scientists can learn more about its safety and correct dosage
They plan to begin phase three by the end of the year.
A coronavirus vaccine is also being developed by Imperial College London.
The Imperial vaccine is in phase one of clinical testing, where doses are being given to a small group of people to determine whether it is safe and to learn more about the immune response it provokes.
Professor Robin Shattock, who is leading Imperial College London's Covid-19 vaccine effort, said data on its efficacy will be available in the middle of next year.
When could a vaccine become available?
A vaccine usually takes years, often decades, to develop, but scientists working on potential coronavirus jabs are hoping to achieve the same amount of work in a few months.
Pfizer and BioNTech plan to apply to the US Food and Drug Administration - the US medicines regulator - by the end of this month for emergency approval to use the vaccine.
The European Medicines Agency said it was still reviewing the safety of the vaccine submitted by Pfizer and BionNTech and has not received clinical trial data.
A "rolling review" of several potential vaccines is under way and, for now, the EU is sticking by its forecast that one may be approved and available "early next year", one source said.
Meanwhile, NHS England chief executive Simon Stevens said the "expectation" is that any vaccination programme would begin in the new year, pending positive results from clinical trials.
Additional reporting AFP