A vaccine would normally take years, if not decades, to develop, but scientists across the world are doing their best to fast-track efforts.

There are around 120 vaccine programmes currently under way. Oxford University and Imperial College London have both started human trials.

US health officials have expressed cautious optimism that a vaccine will be in production by the end of 2020 or early 2021.

Earlier this week, the US's top infectious diseases expert, Dr Anthony Fauci, said the safety and effectiveness of a vaccine against Covid-19 should be known by "early winter".

Dr Fauci said trials of various vaccines would be entering the latter stages of the testing process this month.

"We may be able to at least know whether we are dealing with a safe and effective vaccine by the early winter, late winter, beginning of 2021," said Dr Fauci, the director of the National Institute of Allergy and Infectious Diseases.

SOURCE: BBC