Researchers from Oxford University have received positive results from trials on a vaccine for Covid-19, they claim.
Research published in the Lancet claims an experimental vaccine — labelled ChAdOx1 nCoV-19 — was tested on more than 1000 people and prompted a protective immune response in those aged 18 to 55.
"The vaccine was safe and tolerated," researchers wrote.
"Preliminary results from a phase 1/2 trial involving 1077 healthy adults found that vaccine induced strong antibody & T cell immune responses up to day 56 of the ongoing trial," the Lancet wrote when announcing the breakthrough on social media on Monday night.
"These responses may be even greater after a 2nd dose, according to a sub-group study of 10 participants."
The director of the Jenner Institute Oxford University, Dr Adrian Hill, said the results were hugely promising.
"We are seeing good immune response in almost everybody.
"What this vaccine does particularly well is trigger both arms of the immune system."
He claimed the vaccine causes a reaction in the body's T-cells which help to fight off the coronavirus and that a partnership was already under way with a drug manufacturer to produce millions of doses.
The trial took place between April 23 and May 21. Half of the 1077 participants were given the experimental vaccine.
The scientists wrote that "preliminary findings show that the candidate vaccine given as a single dose was safe and tolerated".
"No serious adverse reactions ... occurred. The majority of adverse events reported were mild or moderate in severity, and all were self-limiting.
"We show that a single dose of ChAdOx1 nCoV-19 elicits an increase in spike-specific antibodies by day 28 and neutralising antibody in all participants after a booster dose.
"Further studies are required to assess the vaccine in various population groups including older age groups, those with comorbidities, and in ethnically and geographically diverse populations.
"We will also evaluate the vaccine in children, once sufficient safety data have been accumulated in adult studies. Phase 3 trials are now under way in Brazil, South Africa, and the UK and will evaluate vaccine efficacy in diverse populations."
The BBC reports that the vaccine is made from a genetically-engineered virus found in chimpanzees that was altered to resemble the coronavirus.
The research is based on the theory that the immune system can learn how to attack the coronavirus when presented with a virus that resembles it.
The news has been welcomed by many, including British Health Secretary Matt Hancock, who tweeted that the UK had "already ordered 100 million doses of this vaccine, should it succeed".