Public confidence in vaccines may be improving in the UK and other parts of Europe but many countries worldwide are seeing growing doubts over immunisations, a new study suggests.

Nations experiencing political instability and religious extremism are seeing increasing scepticism over the safety of inoculations, the researchers said, adding that the spread of misinformation is also posing a global threat to vaccination programmes.

The study is based on data from more than 284,000 adults across 149 countries in what is thought to be the largest global vaccine confidence survey identifying “hesitancy hotspots”.

In the UK, confidence in vaccine safety rose from 47% in May 2018 to around 52% in November 2019.

In contrast, the researchers said, countries such as Azerbaijan, Afghanistan, Indonesia, Nigeria, and Pakistan showed a fall in confidence in the importance, safety, and effectiveness of vaccines.

The findings, published in the journal The Lancet, also raise questions over people’s willingness to be given a Covid-19 vaccination should any of the candidates currently undergoing trials prove successful.

In 2019, the World Health Organisation (WHO) declared vaccine hesitancy as one of the top 10 threats to global health.

As the race to find a Covid-19 vaccine continues, the authors said assessing public attitudes on a regular basis and taking swift action when confidence is declining “must be top priority to give the best chance to ensure uptake of new life-saving vaccines”.

Professor Heidi Larson, from the London School of Hygiene & Tropical Medicine, who led the research, said: “It is vital with new and emerging disease threats such as the Covid-19 pandemic that we regularly monitor public attitudes to quickly identify countries and groups with declining confidence, so we can help guide where we need to build trust to optimise uptake of new life-saving vaccines.”

Prof Larson and her team are currently gathering data on the public’s attitudes towards a Covid-19 vaccine through surveys across the UK and worldwide.

She said initial figures show that willingness in the UK has been variable.

“For instance, at the end of March in the UK it was only 5% of the population – when the fatality rates were high – (who) said that they would not take a Covid-19 vaccine,” she said.

“(In) June that had gone up to about 15% as people saw fatality rates dropping – because people are constantly weighing the imminent threat of the disease and the risk of a brand new vaccine so that’s going to be part of their decision criteria.”

The researchers analysed data from 290 nationally representative surveys conducted between September 2015 and December 2019.

Modelling was used to estimate trends in public perceptions about the safety and effectiveness of vaccines, and the importance of vaccinating children.

Poland was one of the countries in Europe which showed “significant losses” in confidence in vaccine safety – a dip from 64% strongly agreeing that vaccines are safe in November 2018 to 53% by December 2019.

The researchers attribute the fall in confidence to “the growing impact of a highly organised local anti-vaccine movement”.

But they found confidence in vaccine safety to be increasing in other European countries alongside the UK, including Finland, France, Italy, and Ireland.

In France, confidence in vaccines rose from 22% of those surveyed strongly agreeing that vaccines are safe in 2018, to 30% in 2019.

In contrast, six countries, Afghanistan, Azerbaijan, Indonesia, Nigeria, Pakistan and Serbia, saw “substantial increases” in people strongly disagreeing vaccines are safe.

In Azerbaijan, the proportion of those strongly disagreeing that vaccines are safe rose from 2% in 2015 to 17% in 2019.

Researchers described the decrease in confidence as a “worrying trend”, with negative attitudes mirroring political instability and religious extremism.

Indonesia, meanwhile, has seen one of the largest falls in public trust between 2015 and 2019 where the absolute difference in perception of safety fell by 14% percentage points, the team said.

They believe negative attitudes may have been partly triggered by Muslim leaders questioning the safety of the measles, mumps and rubella (MMR) vaccine.

Co-lead author Clarissa Simas, from the London School of Hygiene & Tropical Medicine, said: “Our findings suggest that people do not necessarily dismiss the importance of vaccinating their children even if they have doubts about how safe vaccines are.

“The public seem to generally understand the value of vaccines, but the scientific and public health community needs to do much better at building public trust in the safety of vaccination, particularly with the hope of a Covid-19 vaccine.”