The COVID-19 pandemic has created havoc on a global scale. More than 56 million people have been infected, and more than 1.3 million died as of this writing. In recent weeks, a relaxation of public health and social measures has seen a record rise in cases and deaths in Europe and concerns that surges will occur in other parts of the world. The social and economic consequences of the pandemic are staggering.
No single solution will stop COVID-19. Countries have turned to a multi-pronged approach, involving social distancing, face masks, sanitizing hands and surfaces, public health measures, and, more recently, therapeutics. The announcements of vaccine candidates that may be more than 90% effective have been heralded as potentially providing a safer pathway to herd immunity and a final layer of defense against the virus.
Seroprevalence studies suggest that less than 10 percent of people in most countries have been infected with COVID-19. Hence, most people remain susceptible. To build up herd immunity, a large portion of a community (the herd) should become immune to a disease, making the disease's spread from person to person unlikely. The whole community becomes protected — not just those who are immune. Counting on the infection to build-up herd immunity is likely to lead to many more deaths. A safe and effective vaccine is, by far, the preferable path.
Countries worldwide are grappling with the unprecedented effort required to procure and deploy effective COVID vaccines to so many successfully. Beyond the cost of procurement, vaccinating the world's population will require expanding manufacturing capacity, transportation logistics, cold chains, safe delivery platforms, and equitable mechanisms for allocating doses across and within countries.
However, effective vaccines will only contribute to herd immunity if people accept them and follow the correct vaccination course. The take-up rate is a crucial variable to consider in the quest to achieve herd immunity. For instance, with a 90% effective vaccine, we need a 77.7% take-up rate if the herd immunity threshold is 70%. Currently, the picture is mixed: in a global survey of potential acceptance of a COVID-19 vaccine, positive responses ranged from 55% in Russia to 87% in China. In September 2020, a Pew survey suggested that 49% of American adults would refuse a COVID-19 vaccine.
How can countries address COVID vaccine hesitancy and increase take-up?
The behavioral science literature suggests the importance of understanding the underlying drivers of vaccine decision-making. Countries should design their strategies for vaccine take-up to target these factors, including the perceived risk of disease and side effects, social norms, costs in terms of time and effort, and trust in the health system and government. Behavior science offers options that go beyond traditional behavior change campaigns.
One might imagine that the communication strategy could be quite simple: "take it or risk dying." But we know that depending on age and risk-profile, not everyone is confronted with the same mortality or morbidity risk in case of COVID infection. And so, people who do not feel threatened by COVID might be reluctant to be vaccinated. A revised slogan could then be "take it or risk dying or causing others' death." But will relying on people's self-interest and altruism be sufficient to achieve high enough take-up rates?
One option that has been used for other diseases is mandatory vaccination. School systems require immunization records for enrolment, with some exceptions, and vaccination cards are required to enter some countries.
Mandating vaccination sounds extreme, but medical ethicists argue that a COVID vaccine could be made compulsory if the four following conditions are satisfied: i) there is a grave threat to public health; ii) the vaccine is safe and effective; iii) mandatory vaccination has a superior cost-benefit profile compared with alternatives, and; iv) the level of coercion is proportionate.
However, making vaccination compulsory could wrongly create a perception that COVID vaccines are not safe. Also, given the supply-side constraints that may persist in the short-term, these policies could inadvertently discriminate against individuals who are willing to be vaccinated but do not have access.
Another option is that people could be paid to be immunized instead of using negative incentives to promote immunization,. Vaccines also benefit those in contact with the immunized person, a textbook example of what economists call a positive externality. The social benefit of vaccination is larger than the individual benefit. It makes sense to compensate the individuals for taking the vaccine. In-kind conditional incentives were effective in increasing full immunization rates among young children in India. The Australian government gives tax credits to parents who keep up to date with their children's vaccinations.
Nonetheless, cash or in-kind incentives might be unaffordable as a strategy for many low- and middle-income countries who will already struggle to cover the cost of procuring COVID vaccines. In these contexts, other options have been shown to achieve high coverage for childhood immunizations and may apply in this case, including ensuring vaccines are free of charge, home visits, reminders, and well-designed information campaigns.
Regardless of the mix of interventions, a decline in trust in health workers and the government will stall COVID vaccines' uptake. In 2003, concerns that vaccines were contaminated with harmful agents informed a boycott of a polio vaccination in Northern Nigeria that was led by political and religious leaders. Countries can build trust through clear and understandable communication, informing campaigns with feedback from communities, and mobilizing trusted advocates to lead stakeholder engagement.
As countries work to strengthen the supply-side challenges to procuring and deploying vaccines, they would do well not to ignore the demand-side. National programs can draw on behavioral insights that address the drivers of hesitancy and ensure as many people as possible receive a safe and effective COVID vaccine.