This vaccine survey may not be exactly what it seems
14th Aug 2020
One in six people will refuse a coronavirus vaccine.
This is a misunderstanding of a survey question, which only asked people whether they were “unlikely” to be vaccinated. This isn’t necessarily the same as measuring who will refuse a vaccine, if offered it. Other surveys have shown the number who plan to refuse may be one in seven or one in ten.
“Young people twice as likely to refuse a coronavirus vaccine, study shows”
The Telegraph, 9 August 2020
“Survey sparks concern over misconceptions about vaccines and scepticism about science”
The Guardian, 9 August 2020
“About one in six people (16 per cent) said they would reject [the vaccine], or are likely to.”
The Independent, 9 August 2020
A crucial point went missing this week in an announcement from King’s College London, and in many news reports, about whether people in the UK would get a vaccine for the new coronavirus, if one becomes available.
The reports described research from King’s College, in partnership with Ipsos MORI, which asked 2,237 UK residents between the age of 16 and 75, “If a vaccine for coronavirus becomes available, how likely or unlikely would you personally be to get the vaccine?”
In response, 30% of people said they were “certain” to get it, 23% said they were “very likely”, and 20% said they were “fairly likely”. Another 11% said they didn’t know.
Altogether, 16% said they were either “not very likely” or “not at all likely” or would “definitely not” be vaccinated, which comes to about one in six. The research analysis went on to study this 16% in detail.
The university originally summarised its findings under the headline “Who's most likely to refuse a Covid-19 vaccine?”
I don’t want to, or I won’t?
The problem here is that the question only asked people how likely they thought they were to get the vaccine, not how willing they would be. Some might have thought they were unlikely to get it because they’d already had the disease. Others might have thought the vaccine would only be offered to other people, perhaps those in higher-risk groups, as the flu vaccine already is.
People who do intend to refuse a coronavirus vaccine would probably say they are unlikely to get it too—but from the answers to this question, we can’t tell how many of them there are.
The slides on which King’s College published the data did not confuse unlikelihood with refusal, but in the headline of its press release, and several tweets, as well as most of the subsequent media reporting, the misunderstanding took over.
When we spoke to the researchers at King’s, they agreed that the wording of the question might make people believe they were being asked if they would be offered the vaccine. Professor Bobby Duffy, Director of the Policy Institute at King’s, told us, “We think this is a possible interpretation of the question, but also that it is unlikely to be a common one or a key driver of the patterns of response."
King’s therefore said they would change the headline on their news page to say “Who’s least likely to say they’ll get a Covid-19 vaccine?” (The old page had been removed but not yet replaced at the time this article was published.)
For instance, 23% of the people who said they were unlikely or definitely not getting the vaccine also believed that they had had the disease. Even if they all believed they would not be offered it, or need it, for that reason, that leaves 77% who still might intend to refuse it.
So how many will refuse a vaccine?
Another recent survey, by YouGov, found that about 10% of people in Great Britain would specifically not be “willing” to be vaccinated. This is lower than the 16% who said they were at least “unlikely” to get vaccinated in the King’s survey.
“Although we cannot make exact comparisons due to differences in question wording and response categories,” says Professor Duffy, “[the YouGov] survey is in line with our combined figures of certain/very/fairly likely (73%). While our combined figure for unlikely/definitely wouldn’t is 16% rather than 10%, there are a very large proportion of don’t knows in the other study, which may reflect the uncertainty we pick up in our scaled question.”
Professor Duffy told us that he and his team now intend to conduct a new experiment, to find out how important the wording of the question is. “We’ll publish the results of this as an update to this release, to help inform our own and others’ future questionnaire design,” he said.
What does “fairly likely” mean?
The King’s researchers were unhappy about the way their study was reported for another reason.
Professor Duffy told us, “We have been concerned about some of the media reporting/headlines for this question, where this has been translated into a simple ‘only half of Britons say they would get a vaccine’, which is not how we presented it in the report, press release or webpage – where we were clear that 53% were certain/very likely to, and a further 20% were fairly likely to, and 16% unlikely or certain not to.”
We cannot find any examples of this exact mistake in the media reports we’ve seen, but it may well be difficult to communicate research like this, which measures people’s degree of uncertainty.
For instance, it isn’t clear whether the 20% of people who answered “fairly likely” should be included in the total who will probably be vaccinated. If you are fairly likely to do something, does that mean you probably will do it? Or does it mean that there’s still a large chance you probably won’t?
Based on the YouGov and ORB International surveys, it does seem that a small but significant proportion of the population plan to refuse any coronavirus vaccine. However, it remains unclear what other people feel, and whether this has anything to do with their views on vaccine science.