Thousands more volunteers are needed to take part in the drive to discover a vaccine against Covid-19.
The UK Government said almost 72,000 people had come forward during the past week to register their interest in joining clinical studies but many more are needed.
Ministers hope to get 500,000 people signed up by October, reports the LiverpoolEcho.
The call follows news that a deal had been agreed with pharmaceutical giants GlaxoSmithKline (GSK) and Sanofi Pasteur for 60 million doses of a potential Covid-19 vaccine.
Roger Connor, president of GSK Vaccines, said: "We believe that this adjuvanted vaccine candidate has the potential to play a significant role in overcoming the Covid-19 pandemic, both in the UK and around the world.
"We thank the UK Government for confirmation of purchasing intent, which supports the significant investment we are already making as a company to scale up development and production of this vaccine."
The Government has now signed deals for four separate variations of potential coronavirus vaccines with a total of 250 million doses.
Business Secretary Alok Sharma said: "Our scientists and researchers are racing to find a safe and effective vaccine at a speed and scale never seen before.
"While this progress is truly remarkable, the fact remains that there are no guarantees.
"In the meantime, it is important that we secure early access to a diverse range of promising vaccine candidates, like GSK and Sanofi, to increase our chances of finding one that works so we can protect the public and save lives."
People can sign up for the NHS Covid-19 vaccine research registry via https://www.nhs.uk/conditions/coronavirus-covid-19/research/coronavirus-vaccine-research/
