In this article, I will be exploring the role of behavioural science in the design of effective public health messaging and strategies to encourage uptake, and review the proposed incentive schemes being devised by policy makers to ensure communities reach herd immunity.
Herd immunity is achieved when a sufficiently large proportion of a population are immune to an infection, meaning that infected individuals are unable to propagate the outbreak. Such immunity may be achieved through vaccination or prior infection. Based on studies of the transmissibility of SARS-CoV-2, modellers have estimated that the threshold to reach herd immunity to Covid-19 needs to be at least 75%, with some experts recently having increased their estimate to 90% in view of the emergence of new, more contagious variants.
Achieving such a high level of community immunity through vaccination will be challenging in many countries due to widespread vaccine hesitancy. Countries with initially fast vaccine rollouts, such as Israel, the UK and the US, are now running up against declining rates of acceptance among the remainder of the population that have yet to be vaccinated.
By and large, besides specific requirements for small subsets of the population e.g. health workers in Italy, and all workers in Saudi Arabia, governments have resisted making Covid-19 vaccination mandatory due to fears this could engender resentment and mistrust. Instead, providing information and education has been the first course of action aimed at persuading those who are reluctant to accept a Covid-19 vaccination to do so.
Multiple research studies are underway trying to understand the complexity of vaccine hesitancy, and there is an urgent need to understand how the messaging that will (literally) move the needle needs to be tailored to different segments of the public to overcome their concerns and objections. Behavioural science can help here, with A/B testing taking place to compare the effect of delivering information in different ways, and behavioural scientists seeking to tease apart the cognitive dimensions underlying vaccine hesitancy. The University of California, Los Angeles (UCLA) has run randomized controlled trials (RCT) comparing the effectiveness of text message and video interventions, with results revealing the most effective language to use in text-based nudges to drive people to turn up for their appointments. For example, a key finding was that text reminders that induced feelings of psychological ownership for the vaccine – e.g. claim your dose – were more effective at driving vaccinations than those that did not, while an additional video intervention designed to correct misconceptions failed to yield additional results.
Whilst behavioural science-based approaches such as this can help to increase vaccination acceptance rates at almost zero marginal cost, distrust among some segments of the population remains. Surveys continue to show public reluctance to be vaccinated. The warp speed at which the vaccines have been developed has been hailed as a phenomenal achievement within the scientific community, however, this speed has caused apprehension amongst the general public, especially in light of the link emerging between some of the vaccines and blood clots and the changing guidance from regulators and public health agencies. The politicization of the pandemic, and even denial of its existence in some quarters, further complicate the picture and mean that arming the public with knowledge is insufficient to overcome all objections to vaccination. This makes sense when considering the challenge through a behavioural lens, as confirmation bias shows that vaccine hesitant groups typically assign more weight to their personal beliefs and intuition than empirical evidence. This in turn is compounded by the Dunning-Kruger effect, i.e. the less people know, the more they think they know – altogether meaning that evidence alone cannot overcome biased-information processing.
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There has been a suggestion to entice people to get vaccinated through payment, another classical economic ‘nudge’ in the behavioural science toolkit. Back in August 2020, economist Robert Litan of the Brookings Institute recalled getting vaccinated in childhood and being offered candy or toy to sweeten the shot. He suggested a similar approach could help hurry along herd immunity in the US but, instead of using a trivial treat, giving $1,000 USD to each person who receives the vaccine (due to his hunch that “nothing less would do the trick”). His argument was that, although there would be a significant cost of offering such payments, this would later be offset by avoiding further lockdowns due to herd immunity and would therefore result in a greater saving overall and a quicker economic recovery.
Perhaps one could argue that with Covid-19 vaccines still under Emergency Use Authorisations, their current roll out is effectively a huge scale Real World Evidence study, meaning payment isn’t so different from the incentivisation people receive for participating in phase III trials. The argument in favour of financial incentives was advanced in November 2020 by former Democratic presidential candidate John Delaney, who advocated paying individuals who provide proof of vaccination a sum of $1,500.
Such proposals came under fire by medical ethicists in a viewpoint published in JAMA Network Open in January 2021, arguing that such payments would be both morally flawed and unnecessary, and suggested public funds would be better spent advancing other evidence-based proposals to encourage vaccine uptake. They argued that this policy should be adopted “only as a last resort if voluntary vaccine uptake proves insufficient to promote herd immunity within a reasonable period of time”.
Four months on, amidst the stalling rollout of vaccines, are we at the last resort? What constitutes a reasonable amount of time? And is there a basis of evidence to support this proposal?
We went in search of analogue situations to see if financial incentives have been used for other preventative health measures and how effective they were. We found a systematic review of parental financial incentives for increasing pre-school vaccination uptake from 2014, but it found there was insufficient evidence to conclude whether such interventions were effective. However, other studies reported that they show promise in HIV prevention and smoking cessation. One study of pregnant women in Glasgow, in which one arm was randomised to receive a £400 voucher contingent upon smoking cessation (in addition to the usual cessation support), found the incentives to be highly cost-effective.
And we now have a specific basis of evidence to see how effective payment might be in encouraging uptake of Covid-19 vaccines (although the payments tested were not quite in the magnitude of those suggested above). A recent UCLA survey of over 7,000 unvaccinated Americans showed 34% said they would be more likely to accept a COVID-19 vaccine if they were offered $100 (vs. 31% for $50). On the flip-side, however, 15% reported that this would actually make them less likely to get vaccinated, supporting the argument of the authors of the JAMA viewpoint piece that such payments could backfire and be seen as coercive.
Ethics professor Julian Savulescu disagrees. His reasoning is that people would have the option of accepting this payment (and if poor people are more likely to accept it, well, that’s just the reality of a market economy – as with all risky or unpleasant jobs). And to counter those who consider vaccination a civic duty, he proposes a ‘payment donation’ model that offers altruists the option of donating the payment they would receive for getting vaccinated back to the health service provider. But others argue that it could set a dangerous precedent and – as with the potentially counter-productive step of making vaccination mandatory – fuel anti-vaxxer conspiracy theories.
This backlash against the concept of paying for vaccination hasn’t stopped some private companies and US states from starting to offer bonuses or payments to those who get vaccinated. A number of employers, from Target to Trader Joe’s, are paying their hourly employees for the time they would have to take off to get vaccinated or offering small stipends to those who provide evidence of vaccination. Forbes has compiled a list of more controversial incentives US states and cities are offering to those who get vaccinated – from a $100 savings bond for 16-35 year olds in West Virginia, to unlimited $50 prepaid debit cards for anyone who drives another person to a vaccination site in Detroit. New Jersey’s ‘shot and a beer’ program is one of a number offering non-cash incentives. Evidence suggests this may pay off: a micro-brewery in Buffalo, New York offering free beer to customers visiting the pop-up vaccination clinic next to its taproom this week reported higher uptake than the other first dose clinics in the county combined. In a move to tap into the PR opportunity, Krispy Kreme has also got in on the action, offering a free donut to anyone who shows their vaccination record card. This raises the question of whether there is scope for other actors (even the vaccine manufacturers themselves, who ultimately stand to profit from uptake) to get involved in the payment of incentives.
The UCLA survey data suggests that payment in kind – no need to wear a mask or social distance if you are vaccinated, for instance – may prove more effective among some vaccine hesitant segments of the population. The differences of opinion in groups in the UCLA data – and between experts – highlights that no single one-size-fits-all approach will be successful in overcoming all barriers, meaning a multi-pronged strategy will be required. The Romanian government – faced with one of the highest levels of vaccine hesitancy in Europe - has grabbed headlines by taking the unique approach of offering tourists wishing to visit Dracula’s Castle the opportunity to get a jab without an appointment, and free entry to those who get vaccinated.
At Research Partnership, we use the EAST model of behaviour change as a framework to identify behavioural nudges that will be effective, combining this with attitudinal segmentation to understand which nudges will work in whom. Applicable to any kind of health intervention, this is built around four principles that can encourage uptake:
- (E) make it Easy – as in the above example of not needing to book an appointment to get vaccinated at Dracula’s castle
- (A) make it Attractive – the logic behind the offers of cash, beer, no requirement to wear a mask or free entry to a tourist attraction for those showing proof of vaccination. Or conversely, making it unattractive to refuse vaccination by limiting activities or restricting travel through the use of vaccine passports. What is attractive to one group may not be to another, so there is a need to tailor the offering to people’s existing worldview and core values. This indicates the potential to maximise the cost effectiveness of any financial incentives by targeting them to those who would be most receptive to such an approach rather than applying them as a blanket policy – but in turn raises questions of fairness and how this would be handled.
- (S) make it Social – the rise of the ‘Vaxxie’, the Covid-19 vaccine selfie, is a prime example of this, with celebrities such as Dolly Parton leading the way. Or the converse, naming and shaming those who decline. Spain’s health ministry was planning to implement a (private) register of individuals who refuse to be vaccinated; mandating mask wearing only in unvaccinated people would constitute a more public (but challenging to enforce) shaming.
- (T) make it Timely – such as the text message reminders
Whatever any independent jurisdiction ultimately implements will surely depend not only on their political stance on the matter but also the urgency to contain the pandemic at the time and the economic resources at their disposal. But another obstacle to achieving herd immunity that must be considered is the global unevenness of vaccination, particularly as international travel opens up. In countries facing a situation where much of their population don’t even have the option of getting vaccinated due to supply shortages, the idea that people in other countries are being paid to accept vaccines that would otherwise go to waste is another challenging dimension that will still need to be overcome.