Last month, Pfizer and BioNTech shared additional Phase 1 safety and immunogenicity data from their ongoing USA study of the vaccine candidate, which has advanced into Phase 2/3 evaluation.
The proposed expansion would also allow the companies to enroll people as young as 16 and people with chronic, stable HIV, hepatitis C and hepatitis B, they added.
"The independent review process has concluded, and following the recommendations of both the independent safety review committee and the United Kingdom regulator, the MHRA (Medicine and Healthcare products Regulatory Agency), the trials will recommence in the United Kingdom", the statement from Oxford University said.
The Oxford-AstraZeneca vaccine trial, which is said to be the most advanced vaccine of the corona virus, is about to start again.
Oxford University and AstraZeneca are developing a COVID-19 vaccine, called AZD1222.
The Ministry's officials said that the volunteers will receive LE 250 for each clinical trial, also a follow-up to check their health will be carried out by phone.
"Inevitably with such a large trial there will be times when safety issues arise", said Peter Openshaw, professor of experimental medicine at Imperial College London. The side effects which have been reported so far are mild and expected, like any other vaccine, and no severe side effects have been encountered.
Russian Federation announced last month that its vaccine, named "Sputnik V" after the Soviet-era satellite that was the first launched into space in 1957, had already received approval.
The vaccine candidate is moving towards Phase 3 trial with 30,000 participant enrolment targeted by next week.
Details of the "potentially unexplained illness" in one of the trial's volunteers remains unclear.
Australian Health Minister Greg Hunt has said there is "genuine cause for hope and optimism" that a coronavirus vaccine will be available in the first half of 2021. It is now in the late-stage clinical trials in the US, Britain, Brazil, and South Africa while more trials are planned to take place in Russian Federation and Japan.
Pfizer and BioNTech are looking to expand the enrollment of their Phase 3 COVID-19 vaccine trial to up to approximately 44,000 participants after submitting a proposal to the Food and Drug Administration on Saturday.