Ghana COVID-19 Vaccinations and Financial Incentives

The experiment has four treatments that are delivered in a short video:

Treatment 1: A placebo video that provides general information about the benefit of using solar power to charge household electrical appliances.

Treatment 2: Standard CDC COVID-19 vaccine promotional and information video.

Treatment 3: Low Cash Incentive treatment -- the first 30 seconds are identical to the CDC video -- the last 15 seconds inform viewers that that they will earn $3 if they provide proof of a COVID-19 vaccine within the next 6 weeks.

Treatment 4: High Cash Incentive treatment -- the first 30 seconds are identical to the CDC video -- the last 15 seconds inform viewers that that they will earn $10 if they provide proof of a COVID-19 vaccine within the next 6 weeks.

2022-02-05

2022-03-12

The outcome variable is whether subjects received a COVID-19 vaccine after the initial video intervention. We will begin measuring the outcome for all 6,000 subjects after the six-week reporting period for the Low and High Cash treated subjects. We expect this to begin in approximately one week after the six-week deadline for Low and High cash subjects to indicate whether they had been vaccinated.

We explicitly incorporate design features that will allow us to estimate the spillover effect of the video treatments -- non-treated experimental subjects who are affected indirectly by the COVID-19 video treatments.

The randomized control trial is designed to measure the direct impact of financial incentives on individual vaccine update rates in the Ghana rural population. The clustered randomized control trial will randomly select 6,552 participants from selected rural households; in 312. villages and from 6 Ghana Districts. We adopted a cluster random assignment design in order to address spillover effects that could have important implications for evaluating the overall benefits (and costs) of implementing financial incentives for vaccine uptake.

Village clusters are randomly assigned to receive on of four video treatment arms: a placebo, a standard health message, a high cash incentive ($10) and a low cash incentive ($3). Randomly selected participants within a village will be assigned to one of the four video treatment arms. In addition, a proportion of subjects (25 percent) within village clusters assigned to one of the three treatment arms receive the placebo treatment. We incorporate placebo treatments in the design in order to facilitate the identification of both direct and indirect treatment effects that are decoupled from the delivery mechanism.

The experimental design is described in detail in the attached proposal document.

Villages are randomly selected from population ranked quadruples by a computerized random number generated. Households are randomly selected by random walk instructions. Individuals within households are randomly selected by a coin flip.

Villages, households and individuals within households

Yes

312 Village clusters.

6,500 individuals

1,625

The unit is the individual with a standard deviation of 0.37. The minimum detectable effect size is 0.06.

PAP____Ghana_Vaccination_Incentives-13

We implemented a clustered randomized controlled trial with 6,963 residents in six rural Ghana districts to estimate the causal impact of financial incentives on coronavirus disease 2019 (COVID-19) vaccination uptake. Villages randomly received one of four video treatment arms: a placebo, a standard health message, a high cash incentive (60 Ghana cedis) and a low cash incentive (20 Ghana cedis). For the first co-primary outcome—COVID-19 vaccination intentions—non-vaccinated participants assigned to the cash incentive treatments had an average rate of 81% (1,733 of 2,168) compared to 71% (1,895 of 2,669) for those in the placebo treatment arm. For the other co-primary outcome of self-reported vaccinations 2 months after the initial intervention, the average rate for participants in the cash treatment was 3.5% higher than for participants in the placebo treatment (95% confidence interval (CI): 0.001, 6.9; P=0.045): 40% (602 of 1,486) versus 36.3% (672 of 1,850). We also verified vaccination status of participants: in the cash treatment arm, 36.6% (355 of 1,058) of verified participants had at least one dose of the COVID-19 vaccine compared to 30.3% (439 of 1,544) for those in the placebo—a difference of 6.3% (95% CI: 2.4, 10.2; P=0.001). For the intention and the vaccination outcomes, the low cash incentive (20 Ghana cedis) had a larger positive effect on COVID-19 vaccine uptake than the high cash incentive (60 Ghana cedis).

@Article{Duchetal2023, author={Duch, Raymond and Asiedu, Edward and Nakamura, Ryota and Rouyard, Thomas and Mayol, Alberto and Barnett, Adrian and Roope, Laurence and Violato, Mara and Sowah, Dorcas and Kotlarz, Piotr and Clarke, Philip}, title={Financial incentives for COVID-19 vaccines in a rural low-resource setting: a cluster-randomized trial}, journal={Nature Medicine}, year={2023}, month={Dec}, day={01}, volume={29}, number={12}, pages={3193-3202}, abstract={We implemented a clustered randomized controlled trial with 6,963 residents in six rural Ghana districts to estimate the causal impact of financial incentives on coronavirus disease 2019 (COVID-19) vaccination uptake. Villages randomly received one of four video treatment arms: a placebo, a standard health message, a high cash incentive (60 Ghana cedis) and a low cash incentive (20 Ghana cedis). For the first co-primary outcome---COVID-19 vaccination intentions---non-vaccinated participants assigned to the cash incentive treatments had an average rate of 81{\%} (1,733 of 2,168) compared to 71{\%} (1,895 of 2,669) for those in the placebo treatment arm. For the other co-primary outcome of self-reported vaccinations 2{\thinspace}months after the initial intervention, the average rate for participants in the cash treatment was 3.5{\%} higher than for participants in the placebo treatment (95{\%} confidence interval (CI): 0.001, 6.9; P{\thinspace}={\thinspace}0.045): 40{\%} (602 of 1,486) versus 36.3{\%} (672 of 1,850). We also verified vaccination status of participants: in the cash treatment arm, 36.6{\%} (355 of 1,058) of verified participants had at least one dose of the COVID-19 vaccine compared to 30.3{\%} (439 of 1,544) for those in the placebo---a difference of 6.3{\%} (95{\%} CI: 2.4, 10.2; P{\thinspace}={\thinspace}0.001). For the intention and the vaccination outcomes, the low cash incentive (20 Ghana cedis) had a larger positive effect on COVID-19 vaccine uptake than the high cash incentive (60 Ghana cedis). Trial identifier: AEARCTR-0008775.}, issn={1546-170X}, doi={10.1038/s41591-023-02670-4}}

https://doi.org/10.1038/s41591-023-02670-4