Nearly one in six Britons will refuse a coronavirus vaccine if and when one becomes available, and a similar number are unsure whether they will get one, according to a survey.

The findings come amid a significant rise in anti-vaccination sentiment on social media, and represent a threat to efforts to contain the disease.

“Our hope for a return to normal life rests with scientists developing a successful vaccine for coronavirus,” said Imran Ahmed, the chief executive of the Center for Countering Digital Hate (CCDH), a non-profit organisation that commissioned the research. “But social media companies’ irresponsible decision to continue to publish anti-vaccine propaganda means a vaccine may not be effective in containing the virus. The price for their greed is a cost paid in lives.”

According to the polling carried out by YouGov for CCDH, 16% of British adults “probably” or “definitely” will avoid a Covid-19 vaccine. The poll of 1,663 people found differences between those who get the majority of their news from social media and those who rely more on traditional media: the latter were nine percentage points more likely to say they would definitely or probably get the vaccine.

The 150 largest anti-vaccination social media pages and YouTube channels tracked by CCDH have collected about 8 million more followers since the beginning of the coronavirus crisis, and the 400 outlets in the sample have a combined 55 million followers.

Some of those pages have published false conspiracy theories including that Bill Gates created the pandemic, that vaccines cause Covid-19, and that tests for a coronavirus vaccine have caused women to become infertile.

The majority of the followers are on Facebook, despite the company officially opposing anti-vaccination content. In July 2019 the company announced policies to reduce the spread of posts with “exaggerated or sensational health claims”.

A Facebook product manager said at the time: “People come together on Facebook to talk about, advocate for, and connect around things like nutrition, fitness and health issues. But in order to help people get accurate health information and the support they need, it’s imperative that we minimise health content that is sensational or misleading.”

As well as so-called organic sharing, both Facebook and Twitter have enabled advertising opposing vaccination, despite bans on such promotions on both sites. Those adverts come from influencers including David Wolfe, described by the CCDH as “an anti-vaccine wellness guru”, who promoted a popular panacea, colloidal silver, as “my #1 recommendation under the current crisis”.

The group said: “Other adverts featured Judy Mikovits’ anti-vaxx conspiracy theories, who featured in the notorious Plandemic film, and adverts placed by Robert F Kennedy Jr’s Children’s Health Defense campaign that promote health misinformation about both vaccines and 5G mobile phone signals.”

Advertisers can target their promotions at users who Facebook’s algorithm has decided may have interests such as “vaccine-preventable diseases” or who have liked the page “Talk About Curing Autism”. On Twitter, advertising categories such as “antivaxx” and “natural immunity” are available for all to use.

“This sophisticated ecosystem has grown by exploiting weaknesses in each social media company’s policies on anti-vaxx and health misinformation,” Ahmed said. “Each platform plays a role in feeding and growing the whole.

“Full-time anti-vaxx campaigners doubled their reach by broadcasting their message on YouTube channels that peddle conspiracy theories and false cures. In turn, these campaigners lend their brand and audience of activists to a thriving industry of anti-vaxx entrepreneurs using Facebook as a shopfront.”

Ahmed added: “Both groups have benefited from the reach of professional conspiracists on YouTube and from a network of Facebook groups that turns vaccine sceptics into true believers using psychological hacks like the dopamine hit for ‘likes’ and the fear of abuse for nonconformity.”

In a statement, a Facebook spokesperson said: “We are working to stop harmful misinformation from spreading on our platforms and have removed hundreds of thousands of pieces of COVID-19-related misinformation. We reduce vaccine misinformation in News Feed, we don’t show it in search results or recommend it to you on Facebook or Instagram, we don’t allow it in ads, and we connect people with authoritative information from recognised health experts.”