Cash vouchers provide greater incentive for COVID-19 vaccines than lotteries

By Dr. Liji Thomas, MDJul 30 2021Reviewed by Emily Henderson, B.Sc.

An interesting new study focuses on cash vs lottery incentives to increase the acceptance of coronavirus disease 2019 (COVID-19) vaccines among unvaccinated adults in the USA, finding that the former is significantly more effective than the latter.

Incentive. Image Credit: TypoArt BS/Shutterstock.com

*Important notice: medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

Background

The COVID-19 pandemic, caused by the severe acute respiratory disease coronavirus 2 (SARS-CoV-2), continues to spread, causing disease, death, and economic hardship worldwide. Newly developed vaccines are being deployed on a nationwide scale to combat its spread by achieving population immunity, which will hopefully allow businesses, schools, and transport hubs to open up again.

However, supply shortages and vaccine hesitancy are formidable challenges to meeting those goals. The first can be met only by increasing vaccine manufacture. The second is a matter of beliefs and attitudes. As a result, research is going on to find ways to incentivize vaccination.

Messages on the benefits of COVID-19 vaccination are key to such efforts. They often focus on social responsibility to keep others safe or cite celebrities or other important people who carry weight within the community, or on scientific experts who offer information and reassurance about the vaccine. Vaccine efficacy data, correction of misinformation, and discussing public vaccine-related concerns, are also essential parts of this effort.

However, a sizable segment of the population remains unmoved by appeals to their social conscience or arguments that pitch vaccines as important to their own health as that of others. Thus, many governments have moved to offering financial incentives for those who accept the vaccine.

Typically, such incentives appear as cash, or its equivalent in the form of online vouchers drawn on retailers; or a chance to enter a lottery for an expensive prize or item of daily use. These have been used by the governments in many American states, but their relative value has not been defined.

How was the study done?

The current study was aimed at experimental confirmation of the efficacy of cash vouchers vs lotteries when used to incentivize COVID-19 vaccines. The researchers designed three messages, to identify the most effective among them.

The first is along the lines of the messages sent out by the US Centers for Disease Control and Prevention (CDC), plugging the health benefits, both personal and public, of the vaccine. The second emphasizes the chance to win the jackpot, while the third offers a cash voucher after the vaccine is taken.

The study was published in the pre-print server medRxiv*.

Since, realistically, any vaccine is offered and accepted based on its health benefits, the scientists chose to analyze how the remaining two messages affected the individual’s interest in the vaccine, as a proxy for taking it.

The study included just over 1,600 participants who had not been vaccinated with the COVID-19 vaccines. Basic demographic profiles were prepared based on the answers to five short questions. They were put into one of the three groups by randomized allocation until each group had about 50 participants. The information about the vaccine and incentives was delivered in three short videos

The subjects were then asked to either end the survey or get more information about how to go about booking a vaccination slot in their state.

The digital pathway itself is thus the outcome measure.

What were the findings?

The investigators found that 16% of people who watched the first video said they were interested in further information, and 14% of those who watched the video with the lottery information. However, 22% of people who watched the cash voucher video clicked through for further information.

Thus, the offer of a cash voucher was associated with 53% higher odds of increasing interest in vaccine information. Further analysis confirms these odds, while also showing that White subjects had 30% lower odds of clicking through compared to black subjects.

Conversely, older individuals had about 20% higher odds of expressing continued interest, per additional decade. Whites were also more likely to be interested in the cash voucher offer, at 50% higher odds relative to the controls, while black individuals showed interest in both cash voucher and lottery incentives. However, only a fifth of the sample was made up of black individuals.

What are the implications?

This online experiment shows that in the USA, unvaccinated adults presented with information about vaccination are more likely to follow through if presented with cash incentives than lottery, with the proportion of interested subjects going up from 16% to 22%, respectively.

Incentives are gaining importance as the vaccine-willing fraction of the population has mostly been tapped, in most developed countries. This has led to a fall in the pace of vaccination before population immunity has been reached. With these findings, the scientists found that cash presents a motive to get vaccinated but not lotteries.

Secondly, the experimental design was proved to be an efficient way of answering the question as to whether the offer of incentives could advance vaccination goals. Further research could build on this, by offering varying amounts of cash to identify the existence of a dose-dependent response.

Thirdly, the effect of race on the reaction to an incentive could also be important, as lotteries appeared to be equally attractive to Blacks as cash, but not to Whites. This would require expansion of the sample to capture such differences in the sub-groups that are currently showing higher levels of vaccine hesitancy. The results could help evaluate which cash incentives are affordable and equitable.

Other incentives being used in different regions include prohibiting access to some public places, and the effect of this, and many other vaccine incentives, could also be evaluated using other experimental designs.

Overall, the study demonstrates that financial incentives play a larger role than purely health-related messaging in increasing vaccine interest. Among these incentives, lotteries are less effective than cash vouchers, and in fact, no more of an incentive than the standard health messages.

*Important notice: medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.