The British population has the highest confidence in Covid-19 vaccines, while Japan and South Korea have the lowest, according to a report based on data from an international survey of 15 countries.

The survey, conducted between March and May, showed that the most common reasons for reluctance to vaccinate were concerns about side effects and fears about whether the jabs had undergone sufficient testing.

Other common reasons for respondents included concerns about not getting the vaccine they would prefer and concerns about whether the vaccines are working enough.

“This global survey reveals important information about why people might not offer to take a Covid-19 vaccine if offered to them,” said Ara Darzi, professor at the Institute of Global Health Innovation from Imperial College London.

The YouGov survey recorded the results of more than 68,000 people showed that there are variations across the world, but overall confidence in vaccines is over 50%. The British were the most confident with 87% of them saying they were confident in vaccines, followed by Israel with 83%.

South Korea and Japan got just 47% confidence.

“Our program has been tracking people’s attitudes towards Covid-19 vaccines since November and it is encouraging to see that confidence has continued to grow,” said Sarah Jones, Institute of Global Health co-project leader Innovation.

Confidence in different vaccine brands also varied, with the Pfizer / BioNTech vaccine being the most reliable across all age groups in nine of the 15 countries. Respondents were also asked to record their thoughts on the AstraZeneca / Oxford, Moderna, Sinopharm and Sputnik V jabs.

Americans trusted specific brands the least, and had the highest proportion of people of all ages who said they didn’t trust any of them.

In the UK, the Oxford-AstraZeneca vaccine was most reliable for people under 65 in March, although confidence has declined over time across all age groups.

In most other countries, confidence in the Oxford-AstraZeneca vaccine was low, as with the Sputnik V and Sinopharm vaccines.

The surveys were carried out in Australia, Canada, Denmark, France, Germany, Israel, Italy, Japan, Norway, Singapore, South Korea, Spain, Sweden, UK and the United States.