King's College London

The public’s preference for the AstraZeneca Covid vaccine has declined since last month, and belief that it causes blood clots has increased – but despite this, vaccine confidence is higher than it was towards the end of 2020, and there has been a big rise in the proportion of people who say they want to be vaccinated as soon as possible, according to a new study.

The research, by the University of Bristol, King’s College London and the NIHR Health Protection Research Unit in Emergency Preparedness and Response, is based on a survey of 4,896 UK adults aged 18 to 75 conducted between 1 and 16 April 2021. This follows up a study in Nov/Dec 2020 and tracks some of the same individuals to see how their views have changed and why.

The AstraZeneca vaccine and blood clots

17% of the public now say they’d prefer to have the AZ vaccine, if they had a choice of any – down from 24% towards the end of March.

And 23% of people now believe the AZ vaccine causes blood clots – up from 13% last month. But the public are still most likely to say this claim is false (39%) or that they don’t know whether it’s true (38%).

And within this latest survey wave, there is a big difference in beliefs before and after the MHRA announced there was a possible link between the vaccine and extremely rare blood clots on 7 April: 17% of those interviewed in the first week of that month thought this claim was true, compared with 31% interviewed after.

There are also big differences in views on this issue among different groups:

• Vaccine-hesitant people (57%) are more than twice as likely as both the public overall (23%) and the vaccine-confident (23%) to believe the AZ vaccine causes blood clots.
• Those who have received an invitation to get vaccinated but not taken it up are also much more likely to believe the vaccine causes clots: 54% think this claim is true, compared with 30% of those who have received their invitation and plan on attending soon.

Vaccine confidence is still strong

A growing belief that the UK’s main Covid-19 vaccine is linked to blood clots has not dented overall levels of confidence in vaccines in general.

81% now say vaccines are safe, compared with 73% who said the same towards the end of 2020. This include 39% who strongly agree that this is the case – up from 30%.

There has been a similar change in views of how well vaccines work: 86% say they are effective, an increase from 79% in Nov/Dec 2020. And the proportion who strongly feel this way has risen from 38% to 47%.

There has been an increase in eagerness to get a Covid vaccine – though a minority have become more definitely against vaccination

• 46% of those who are currently unvaccinated say they’re certain to accept a vaccine when offered it. This compares with 36% of the public overall who said they were certain to in Nov/Dec 2020 and 30% in July of that year, when asked how likely they would be to get a vaccine once it became available.
• In total, 73% say they’re at least fairly likely to get the vaccine now, which is the same proportion as in both Nov/Dec and July 2020.
• But at the other end of the spectrum, there has been an increase in those saying they are not at all likely or definitely won’t get the vaccine, from 7% in July 2020 to 13% in this latest study.
• 63% of those who say they might get a Covid vaccine would now prefer to have it as soon as they’re offered it – double the 29% who said they’d like to have a vaccine immediately after it became available in Nov/Dec last year.
• And in Nov/Dec 2020, people from ethnic minorities were particularly unlikely to say they wanted to get the vaccine straight away – but there has been a big change in views since. Among those from minority ethnic groups who say they might get a Covid vaccine, 45% would now prefer to be vaccinated immediately after being invited – three times the 15% who said they’d like to get the vaccine as soon as it became available last year, before the rollout had begun.

The reasons for increased willingness to be vaccinated are to go on holiday and protect families and the wider community

This study included a longitudinal sample, following the same individuals that were interviewed in Nov/Dec 2020. This allowed the researchers to compare responses on vaccine intention from that previous study with the current study, and ask those who changed their minds what had caused that change.

The clear top reason for switching from not wanting to get the vaccine to wanting to be vaccinated was the wish to go on holiday, including the possibility of vaccine passports, mentioned by 18% of switchers.

The top two reasons given by those who were uncertain and are now sure they want the vaccine is that it is the “right thing to do” (19%) and to protect their own family or others in general (12%).

Professor Bobby Duffy, director of the Policy Institute at King’s College London, said:

“The blood clot scare has affected how some of the public view the Astra Zeneca vaccine – but has not reduced confidence in vaccines overall. In fact, the trend has been towards increased commitment to get vaccinated – and quickly – as the rollout has progressed so well, with no sign of serious widespread problems. People have had more time and real-world experience to help them make up their minds.

“However, this also means that the naturally sceptical have also affirmed their views, with a near doubling since July last year – from 7% to 13% – of those who say they are not at all likely to or definitely won’t get vaccinated. This shows there is still no room for complacency in clearly communicating the vital benefits of vaccination, given the need to cover a very large proportion of the population in order to truly contain the virus.”

Dr Siobhan McAndrew, Senior Lecturer in Quantitative Social Science at the University of Bristol, said:

“These findings shed light on different aspects of coronavirus vaccination hesitancy: concern regarding long-term side effects, vaccine effectiveness, vaccine ingredients, effectiveness and speed of regulatory clearance stand out. Such concerns continue for a hard core of the vaccine-opposed.

“The public health challenge remains complex: to respond to the concerns and information needs of a diverse population, to support the pro-vaccine social norm, and to offer meaningful reasons to take up the vaccine to those who remain unconvinced.”

Technical details
Ipsos MORI interviewed a sample of 4,896 adults aged 16-75 in the United Kingdom between 1 and 16 April 2021. Data has been weighted to the known offline population proportions for age within gender, government office region, working status, social grade and education. All polls are subject to a wide range of potential sources of error.

The findings in this study are part of “Covid and after: trust and perceptions”, a project funded under the ESRC Covid-19 Rapid Response research call ES/V015494/1.