Testing of a Covid-19 vaccine has little hope of proving successful in the UK – unless there is a new spike in the disease.
Professor Sarah Gilbert, who is leading the University of Oxford vaccine trial, said there is little chance of proving whether the vaccine is effective based on the UK trial, because transmission of the virus is low.
She said lockdown had limited spread of the condition in the UK making it difficult to gauge effects of the vaccine.
She told the Lords Science and Technology committee: “Of course, what happened was that because it (transmission) actually increased much more rapidly than anybody thought was going to happen, we had the lockdown, which fortunately reduced transmission.
“Not so fortunate for those of us trying to develop vaccines in the UK, because we now have essentially a very large safety immunogenicity study running in the UK with little chance, frankly, of determining efficacy.”
Speaking to United Nations ambassadors earlier this month, she said: “Unless some of the trial participants do become infected, we cannot know that the vaccine is effective.
“We are thus focusing on vaccinating healthcare workers, as they have the highest rates of virus infections. Further, as measures to ease the lockdown are being introduced, transmission may rise again.
She told the committee the researchers’ approach was to work with multiple different countries in different settings to give them the best chance of seeing efficacy in at least one of those countries.
The vaccine is still expected to be rolled out in the autumn.