The Government has ordered 90 million doses of vaccines under development by Belgian pharmaceutical company Janssen and US biotech company Novavax, the BBC has reported.
Kate Bingham, chair of the UK government Vaccine Taskforce, told the BBC that there has never been a licensed vaccine for a coronavirus.
"We don't know if any of these vaccine formats that we've acquired will actually work", she said.
"There are no licensed vaccines for any human coronavirus."
Human trials of the vaccine, ChAdOx1 nCoV-19, suggest it is safe and induces an immune response to Covid-19.
Early results indicate the jab could provide double protection – generating an immune response which stimulates the body to produce both an antibody and T-cell response.
Health Secretary Matt Hancock has ordered 100 million doses of ChAdOx1 nCoV-19.