Figures show they account for 15% of participants.
People from all communities, and especially those from Black, Asian and minority ethnic communities, are encouraged to take part in NHS-supported vaccine studies into Covid-19 after Oxfordshire figures show under-representation in these communities.
According to Public Health England, people from Black communities are statistically more likely to be diagnosed with Covid-19, and death rates are higher for Black and Asian ethnic groups, but we don't yet know why.
A total 335 out of 4,718 county people who have signed up for the NHS Covid-19 vaccine research registry are from ethnic minority communities.
The registry, which was launched in July, invites people who are aged 18 and over to provide their details so they can be contacted about taking part in vaccine trials taking place across the UK.
People from all communities are needed to ensure vaccines being trialled will be effective for everyone.
Of those who signed up, 23 were Black, African, Black British or Caribbean, making up 0.49% of local sign ups to the registry. This compares to 1.8% of the county's population in this ethnic group, or 11,424 people (2011 census, all ages).
A further 183 Asian or Asian British people signed up, representing 3.88% of registrations compared to 4.9% of the county's population, 31,657 people, in this ethnic group (2011 census, all ages). 92.75% of county registrations were white.
There is no obligation to take part in a vaccine trial and people can withdraw their details at any time. Users also have the option to be contacted about other research they could take part in. More than 300,000 have registered nationally.
Professor Najib Rahman, Director of the Oxford Respiratory Trials Unit at the University of Oxford and a member of Consultant Respiratory and Pleural Physician at the Churchill Hospital, Oxford, said: "A significant amount of data from the last six months of the Covid-19 pandemic suggest that individuals from Black, Asian and ethnic minority backgrounds may be affected more severely by the virus.
"It is therefore of key importance that people from these communities are able to participate in research on Covid-19, especially concerning the vaccine and its potential to reduce the transmission rate and reduce severity of disease."
Dr Maheshi Ramasamy, Consultant in Infectious Diseases and Acute General Medicine and Principal Investigator at the University of Oxford's Oxford Vaccine Group said: "We know that people from Black, Asian and minority ethnic backgrounds are disproportionately affected by Covid-19 in terms of severe disease and mortality.
"So when we do have a vaccine that we roll out to the general population, it's really important that we can demonstrate to people from these communities that we have evidence that the vaccine works."
Chair of the Government's Vaccine Taskforce, Kate Bingham said: "The only way to check how well a coronavirus vaccine works is to carry out large-scale clinical trials involving thousands of people. Researchers need data from different communities and different people to improve understanding of the vaccines. The only way to get this is through large clinical trials.
"We want to ensure the data we get actually represents the different people from different backgrounds in the UK. This includes people who are over 65, frontline healthcare workers, or have existing health conditions, and we need people from the communities which have been disproportionately affected by the pandemic from Black, Asian and other minority ethnic backgrounds."
You can sign up to the NHS Covid-19 vaccine research registry here.