As the front-runner in the global rasce for a vaccine entered final Phase III clinical trials, researchers at Bristol University carried out tests to check whether it was behaving as intended.
Scientists then have the space to add in new instructions to make a so-called coronavirus “spike protein” – which the immune system then attacks.
This means it is impossible for the vaccine to replicate or cause disease in humans, but it can still be produced in the laboratory under special conditions, according to the researchers.
The Bristol team found that the vaccine was successfully able to instruct human cells to copy the genetic instructions to create the spike protein.
Once the spike protein is made, the immune system reacts to it and this pre-trains the immune system to identify a real infection, they explained.
Dr David Matthews, from Bristol’s School of Cellular and Molecular Medicine (CMM), who led the research, said: “Until now, the technology hasn’t been able to provide answers with such clarity, but we now know the vaccine is doing everything we expected and that is only good news in our fight against the illness.’
Sarah Gilbert, who leads the Oxford University vaccine trial, praised the study for helping to explain the vaccine’s effectiveness.
She said: “The study confirms that large amounts of the coronavirus spike protein are produced with great accuracy, and this goes a long way to explaining the success of the vaccine in inducing a strong immune response.”
The results were released as the Government’s chief scientific adviser warned that a widespread roll-out of a vaccine for Covid-19 is unlikely to take place before next spring.
Sir Patrick Vallance said that while there has been “remarkable” progress made around the world, vaccines will not be in widespread use until some time next year.
Speaking at a Downing Street press briefing on Thursday, he said it was too early to speculate about how effective a vaccine might be, but said the aim would be for a vaccine to allow the “release” of measures such as social distancing and mask-wearing.
“That’s got to be an aim that we would all wish for and that’s why so many companies around the world are working on vaccines and why there has been such remarkable progress,” he said.
“Things are progressing well, there are vaccines that produce an immune response, they’re in phase III clinical trials, we should be seeing some data read-outs over the course of this year, but I remain of the view that the possibility of wider-spread use of vaccines isn’t going to be until spring or so next year by the time we get enough doses and enough understanding of the outputs to use them.
“Now we may get a few doses this side of Christmas, maybe something could happen, but I think we should more realistically be looking at spring, and of course there are no guarantees until the studies have read out.
“So we need to be cautious and carry on, but there is a good progress in terms of the vaccines,” Sir Patrick added.
Earlier this week, Sir Patrick said that only one disease – smallpox – had ever been completely eradicated.
Giving evidence to the joint committee on National Security Strategy, he said that in the future – treating Covid-19 may become more like seasonal flu.
He said that over the next few months it will become clear whether there are any vaccines that do protect, and how long for, adding that while a number of candidates cause an immune response, only phase three trials will indicate whether they stop people from being infected.