The UK has signed deals for two more potential coronavirus vaccines.
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.
They are the fifth and sixth experimental vaccines the UK has ordered. Most vaccine trials end in failure, and there is no guarantee that a viable Covid-19 vaccine will be rolled out.
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."
A vaccine being developed at the University of Oxford is currently one of the most promising potential options.
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.
