Professor Robin Shattock said his team would instead be using the RNA technology behind the vaccine to target new and emerging coronavirus variants that have been identified across the world.
“Although our first generation Covid-19 vaccine candidate is showing promise in early clinical development, the broader situation has changed with the rapid roll out of approved vaccines,” Prof Shattock said in a statement on Tuesday.
“It is not the right time to start a new efficacy trial for a further vaccine in the UK, with the emphasis rightly placed on mass vaccination in response to the rapid spread of the new variant.”
He said his team would begin working to develop the vaccine technology as “a safety net to catch escape mutations, reach variants that other vaccines may not and meet potential needs for annual booster vaccinations.”
Similar in design to the Moderna and Pfizer/BioNTech vaccines, the Imperial College jab makes use of self-amplifying RNA to deliver genetic instructions to human muscle cells, which then go on to produce the ‘spike’ protein found on the surface of Sars-Cov-2.
Spotting what appears to be foreign invaders within the body, the immune system springs into action to produce the necessary antibodies and T-cells, inducing protection.
Phase one and two trials for the vaccine were launched last summer amid the global race to develop an effective Covid-19 jab.
Some 400 volunteers, aged between 18 and 75, were injected with two doses of the vaccine over a four-week period.
At the time, it was hoped that the vaccine would progress to its phase three trial at the beginning of 2021 before securing approval in the summer.
However, as the UK continues to push ahead in its rollout of the Oxford and Pfizer vaccines, with more than 6.5 million first doses administered to date, Imperial College London has decided to switch focus.
The results of the phase one and two studies are still pending, and will inform the next steps of development, the university said.
Imperial’s self-amplifying RNA technology can be adapted to target new variants and mutations of Sars-CoV-2. This capability could be central in developing second generation vaccines for Covid-19 as the pandemic progresses.
The team has also developed approaches that could enable RNA vaccines to be stored in ordinary refrigerators for months, rather than the extremely low temperature required by the current RNA vaccines.
Prof Shattock said Imperial College was “working with philanthropists, investors, government and industry partners to take this exciting technology further”.
Having already committed millions to the vaccine project, the government will continue to support the development of the university’s self-amplifying RNA technology in relation to Covid-19 and future infectious diseases.
Professor Alice Gast, president of Imperial College London, said: “Imperial’s self-amplifying RNA vaccine has much to offer in the fight against coronavirus and other diseases.
“This exciting technology will help accelerate future vaccine production, providing the agility to defend against viral mutations, and protect current and future generations from pandemics.”