Researchers surveyed over 5,000 adults about an approved jab for the NHS.
New data by Oxford University has revealed just over a quarter of people in the UK are hesitant about getting the COVID-19 vaccine.
The Oxford team found some of those who were unsure didn't see themselves as at risk, doubted the effectiveness of the vaccine or were worried about side-effects.
Others in that group had negative views of doctors, poorer NHS experiences, or concerns about the financial motivations of vaccine developers.
72% of people questioned said they were willing to be vaccinated though.
16% are 'very unsure' and 12% are 'strongly hesitant', according to the research.
Professor Daniel Freeman from the Department of Psychiatry at The University of Oxford, said: 'Vaccine hesitancy is mistrust of a vaccine: that it is not needed, it will not work, or it will not be safe. Strikingly, those who are hesitant are not bringing to mind the benefit to everyone of taking a COVID-19 vaccine. There are also suspicions that the virus is no worse than the flu and that vaccine side effects won't be known until later.
'It is often rooted in deeper mistrust, including negative views of doctors, anger at our institutions, and sometimes even outright conspiracy beliefs. People will avoid getting vaccinated rather than feel like a guinea pig, experimented on by those they view as not caring about them.
'We need strong messaging that taking a vaccination is actually a duty we need to do for the benefit of everyone. Most people can see vaccination as the light at the end of the tunnel, but they are also looking for detailed information on the topic that they can trust.
'They want reassurance that the speed of development has not compromised safety. They want thorough information on effectiveness, safety, and how long protection will last.'
According to the Oxford University data, approximately a quarter of the population are entertaining the idea that the virus is a hoax, with around one in five people thinking that vaccine data may be fabricated, and another one in four people unsure whether such data are made-up.
Dr Sinéad Lambe, study team member, said: 'It is a mistake to dismiss vaccine hesitancy as unconsidered. Even when sceptical, people have weighed up a number of issues in their decision-making.
'Understanding their concerns is essential if we are going to provide the right information and necessary assurances to increase public confidence in the new vaccines.'
Vaccine hesitancy was higher in younger people, females, and those on lower incomes, but these were only very small associations, indicating hesitancy is evenly spread across the population.