More than 100 people will take part in the next phase of clinical trials to test a new coronavirus vaccine developed at Imperial College London.
Work began earlier this week to vaccinate a larger number of participants to assess the optimal dosage of Imperial’s Covid-19 vaccine candidate.
It follows a “successful” initial phase of the trial which involved 15 volunteers, Imperial said.
Neither the participants nor clinical staff will know which dose they have received, Imperial said.
Professor Robin Shattock, who is leading the development of Imperial’s vaccine, said: “The progression to the next phase of the trial is an important step in assessing the safety of our vaccine.
“Analysing blood samples for antibodies and T-cell response will provide some indication of whether our vaccine can produce an immune response to fight the virus.”
Prof Shattock said larger clinical trials will still be required to determine whether the vaccine candidate is able to reduce the spread or severity of coronavirus.
The first 15 volunteers involved in the initial phase of the trials will return to receive a second booster dose in the coming days.
Imperial said all participants were being closely monitored by a clinical team, who will record any potential adverse reactions and analyse participants’ blood for the presence of neutralising antibodies against the virus.
The trials are the first test of a new self-amplifying RNA technology, which Imperial said had the potential to “revolutionise vaccine development” and enable scientists to respond more quickly to emerging diseases.
The vaccine was found to be safe in animal studies and produced “encouraging” signs of an effective immune response against the Sars-CoV-2 virus, Imperial said.
It has been developed following more than £40 million in funding from the Government and further support from hundreds of donors.
Pre-clinical findings published in Nature Communications in July showed two doses of the vaccine produced “highly specific” neutralising antibodies against Sars-CoV-2 in mice, which were able to neutralise the virus, Imperial said.
Dr Katrina Pollock, clinical lead on the Imperial Covac1 study, said: “We have had a promising start but it remains too early to speculate whether our vaccine candidate will be effective in preventing infection.”