England's chief medical officer has admitted people with "very weird views" about vaccination may not be persuaded to have a coronavirus jab.
Professor Chris Whitty acknowledged there may be members of the public who are hesitant about getting the vaccine, but said there is a difference between them and opponents of vaccination.
He told MPs there is a "very small group" who would not be persuaded that having a vaccine is the right thing to do, but added that these people have the right to refuse and make their own choices.
His comments came after the first jabs were administered on Tuesday, with the NHS vaccination programme continuing across the UK.
"There is a very small group of people who have got very weird views about vaccines," he told a joint session of the Commons Science and Technology and Health and Social Care committees.
"In a sense, they're not worth worrying about in public communication terms, because nothing will persuade them that this is the right thing to do, and that's their right as competent adults to make those choices.
"There is a lot of people, though, who actually have quite legitimate questions of any vaccine and any medical treatment. Vaccines are no different to that."
Asked about a report by the British Academy and the Royal Society, which said messaging around vaccines should be an open dialogue, Prof Whitty urged transparency and honesty.
He said people wanted to know three things about any medical treatment: is the problem big enough to do something about it, does the treatment work and what are the side effects.
"They need to have those, as you say, the Royal Society said it rightly, and I think we would all agree with this, as transparently and honestly as possible," he said.
"So that people aren't surprised, they actually can ask straight questions and get straight answers."
Prof Whitty said his deputy chief medical officers, Dr Jenny Harries and Professor Jonathan Van-Tam, had done a "great job" of answering questions on vaccination, and he told the committee on Wednesday that this push for transparency needed to continue as more information on the jabs emerges.
"A lot of the people you are talking about, who are just waiting to see, that's entirely reasonable. These are new vaccines," he told MPs.
"They are waiting to see and I think with the right information they will think, yes actually, this feels right to me and that's what they will do."