Vaccination is the most important instrument to sustainably contain the COVID-19 pandemic. In an unprecedented worldwide effort, multiple vaccines have been successfully developed in record time. However, in order to stop the pandemic, it is estimated that 60–70% of the population needs to be vaccinated.[1;2] Recent survey evidence suggests that this threshold cannot be met in many countries.[3;4] Since a consensus has emerged in most countries that compulsory vaccination is not a viable option, the question is how to convince citizens to participate in the vaccination programme. Decision makers therefore currently debate which strategies can increase vaccination uptake. In a recent study, we contribute to this discussion by evaluating the effectiveness of three strategies that governments can adopt, and by identifying for which kinds of populations different approaches are more effective.

We tested the effect of three strategies that governments can apply to raise the willingness to get vaccinated against COVID-19: granting freedoms, financial remuneration, and vaccination at local doctors. The first strategy, granting freedoms, refers to policies that only reinstall certain liberties to people who are vaccinated while penalizing those without a vaccination. The second strategy, financial remuneration, refers to providing citizens with monetary incentives to encourage vaccination uptake. A large body of research in behavioural and health economics has shown that monetary incentives can be an effective instrument to steer human behaviour.[5; 6; 7] The third strategy, vaccination at local doctors, rests on two ideas; namely, the reduction of transaction costs and increasing trust. A large body of research has demonstrated that transaction costs are a major reason for citizens not to uptake services, [8] while research on vaccination hesitancy has shown that trust is a major predictor for vaccination uptake.[9] Allowing local doctors to vaccinate citizens instead of only administering the vaccine roll-out through vaccination centres can increase trust and reduce transaction costs (e.g., bureaucratic registration systems, inconvenient and distant locations or wait times).

To evaluate the effectiveness of these strategies, we designed an experimental study embedded in a nationally representative survey fielded in Germany. We recruited 20,500 respondents from 5^th March to 25^th March 2021. Among our sample, we found that 7% of the respondents were vaccinated and 60% would accept a vaccine if it were available to them. This is close to the low bound for herd immunity. Another 17% remained undecided, and 16% would refuse to get vaccinated. Moreover, the arguments given for vaccine hesitancy are not specific to the German context. When respondents in our sample give an account for their hesitancy, about two thirds describe concerns over the side effects or adverse long term effects of the vaccine, with fewer (19%) discounting the seriousness of Coronavirus. These features give some confidence that findings from Germany have implications that extend beyond this specific case.

In our experimental study, participants were randomly exposed to vignettes of a hypothetical policy context that varied along three dimensions: freedoms for vaccinated people (yes, no), financial incentives for vaccination (no, 25 Euros, 50 Euros), and vaccination at local doctors instead of vaccination centres (yes, no). Subsequently, respondents were asked about their willingness to get vaccinated under these different policy scenarios.

Our results show that all strategies have the potential to increase vaccination uptake, but that the effect varies in size and by prior vaccine hesitancy. The respondents who are hesitant are overall less likely to respond to any of these strategies. However, for those who remain undecided, receiving 50 Euros for vaccination increases the share of the respondents who say that they will get vaccinated by 5 percentage points. Similarly, the possibility to get vaccinated at the local doctor increases the share by 5 percentage points. We observe the strongest effect (6 percentage points) among the undecided through the use of the personal freedoms strategy.

While all three strategies have positive average effects, our findings thus suggest that the scope for altering behaviour among the truly hesitant respondents is limited. Governments can do better by focusing on undecided citizens for whom the combined effects could be as high as 13 percentage points. In addition, the choice of strategy depends on the age profile of undecided citizens; governments seeking to increase vaccination uptake among undecided younger cohorts may see greater returns from enhancing freedoms, while governments focused on undecided older citizens will see greater returns from ensuring vaccine provision at local doctors.

In conclusion, vaccination is the key to overcoming the COVID-19 pandemic. Our study shows that governments can noticeably increase vaccination uptake in the population through appropriate strategies. This increase in vaccination readiness can become a crucial building block in the near future when it comes to vaccinating a sufficient number of citizens to establish herd immunity in order to stop the Coronavirus pandemic.

 

For more information, see:

Klüver, H., Hartmann, F., Humphreys, M., Geissler, F., & Giesecke, J. (2021, May 9). What incentives can spur Covid-19 vaccination uptake?. Retrieved from osf.io/ax6pw

References

[1]     Aschwanden, C. The false promise of herd immunity for COVID-19. Nature 587, 26–28 (2020).

[2]     Randolph, H. E. & Barreiro, L. B. Herd Immunity: Understanding COVID-19. Immunity 52, 737–741 (2020).

[3]     Lazarus, J. V., Ratzan, S. C., Palayew, A., Gostin, L. O., Larson, H. J., Rabin, K., Kimball, S. & El-Mohandes, A.A global survey of potential acceptance of a COVID-19 vaccine. Nature Medicine (2020).

[4]     Sallam, M. Covid-19 vaccine hesitancy worldwide: A concise systematic review of vac- cine acceptance rates. Vaccines 9, 1–15 (2021).

[5]     Kamenica, E. Behavioral economics and psychology of incentives. Annual Review of Economics 4, 427–452 (2012).

[6]     Giles, E. L., Robalino, S., McColl, E., Sniehotta, F. F. & Adams, J. The effectiveness of financial incentives for health behaviour change: Systematic review and meta-analysis. PLoS ONE 9 (2014).

[7]     Munzert, S., Selb, P., Gohdes, A., Stoetzer, L. F. & Lowe, W. Tracking and promoting the usage of a COVID-19 contact tracing app. Nature Human Behaviour (2021). URL https://doi.org/10.1038/s41562-020-01044-x.

[8]     Currie, J. The Take-up of Social Benefits. In Auerbach, A. J., Card, D. & Quigley, J. M. (eds.) Public Policy and the Income Distribution, 80–148 (Russell Sage Foundation, New York, 2006).

[9]     Yaqub O, Castle-Clarke S, Sevdalis N. & Chataway J. Attitudes to vaccination: A critical review. Social Science and Medicine 112 (2014).

 

Prof. Dr. Heike Klüver is Professor of Comparative Political Behaviour at Humboldt-Universität zu Berlin.

Felix Hartmann is Postdoctoral Research Fellow at the Research Group for Comparative Political Behaviour at Humboldt-Universität zu Berlin.

Prof. Macartan Humphreys is Professor of Political Science at Columbia University in New York and Director of the Institutions and Political Inequality Group at the WZB Berlin Social Science Center.

Dr. Ferdinand Geißler is Postdoctoral Research Fellow at the Research Group for Empirical Social Research at Humboldt-Universität zu Berlin.

Prof. Dr. Johannes Giesecke is Professor of Empirical Social Research at Humboldt-Universität zu Berlin.