Reminders, but not monetary incentives, increase COVID-19 booster uptake

The Influence of Financial Incentives on Vaccination Hesitancy: A Narrative Review of Recent Research

BACKGROUND

Vaccine hesitancy represents a significant global health challenge that greatly hinders public health efforts focused on managing the transmission of infectious diseases. A wealth of original research conducted worldwide has examined various incentives that could help alleviate vaccine hesitancy and increase vaccination rates. Although some findings are conflicting, no comprehensive review has yet assessed the overall effectiveness of these strategies. This study aims to bridge this knowledge gap by examining how financial incentives influence people's willingness to undergo vaccination.

METHODS

In August 2024, we extensively searched four databases for studies focusing on financial incentives and vaccination rates. Examples of financial incentives included lottery tickets and hypothetical or physical monetary rewards ranging in various amounts depending on the study. We selected nineteen relevant articles from a larger pool and evaluated them for validity and bias.

RESULTS

Around eighty percent of the research focused on COVID-19 vaccines, driven by the ongoing pandemic and the debates surrounding their use. Most of the studies indicated a positive influence of financial incentives on vaccination rates, although they often came with a higher risk of bias. Conversely, several studies suggest that financial incentives do not result in benefits. Instead, they highlight other factors that have a more profound effect on influencing people to undergo vaccination. The remaining studies are inconclusive regarding the effectiveness of financial incentives, concluding the need for further research. The strategies to mitigate these concerns included a combination of legal and monetary incentives.

SUMMARY

The effectiveness of financial incentives in boosting vaccination rates seems to differ significantly based on the region and context. They tend to be more effective in economically disadvantaged developing countries. In contrast, in developed nations, they may be ineffective or counterproductive due to various confounding factors such as financial background, lack of trust in the healthcare system, and/or lack of patient education. In resource-rich areas, educational programs often yield better results, and addressing widespread mistrust in healthcare systems and governmental policies through transparency is essential. Ultimately, employing tailored incentives alongside public education could enhance vaccination acceptance, particularly in culturally diverse countries like the United States, where understanding community preferences is crucial.

Financial Incentives for COVID-19 Vaccination: A Cluster Randomized Clinical Trial

Importance

Prior studies found that financial incentives have small, positive direct effects in increasing COVID-19 vaccination rates, but unmeasured social spillovers (ie, changes in outcomes among untreated individuals who are socially exposed to policy beneficiaries) may diminish the overall effect of such policies.

Objective

To assess the spillover effects of a COVID-19 vaccination financial incentive and assess whether incorporating estimates of spillover meaningfully affects broader evaluations of policy effectiveness.

Design, Setting, and Participants

This population-level, address-cluster randomized clinical trial was conducted in November 2021. Participants were all adult (aged ≥18 years) residents of Ravensburg, Germany, who were randomly assigned to the treatment or control group. One resident in each address cluster was randomly selected to be an address-cluster representative. Address-cluster representatives in the treatment group received the treatment letter; all other cohabitants at that same address received the control letter. All individuals in addresses randomly assigned to the control group were mailed a control letter. Intention-to-treat data analysis was conducted from January 2022 to May 2024.

Intervention

Control letters informed recipients about 7 upcoming free COVID-19 vaccination events. Treatment letters were identical to control letters, except they also offered €40 (US $41.46) for getting vaccinated at one of the events.

Main Outcome and Measure

Primary and booster COVID-19 vaccination uptake was observed and recorded on site during the public vaccination events. Primary vaccinations were defined as either the first dose of a 1-dose vaccine or the first or second dose of a 2-doses vaccine. Boosters were defined as any dose after primary vaccination. Three types of commonly used treatment effects were analyzed: direct, spillover, and overall.

Results

Among 41 548 Ravensburg residents (mean [SD] age, 49.96 [19.04] years; 51.3% female), 796 (1.9%) were vaccinated at 1 of the 7 public vaccination events. The direct, spillover, and overall effects of receiving a financial incentive on primary vaccinations were all nonsignificant. For booster vaccinations, the direct effect was negative but not statistically significant (-0.32 percentage points [95% CI, -0.77 to 0.14 percentage points]; P = .17), whereas the overall effect (-0.30 percentage points [95% CI, -0.51 to -0.09 percentage points]; P = .006) was significantly negative. The spillover effect was significantly negative (-0.29 percentage points [95% CI, -0.53 to -0.06 percentage points]; P = .01), but only for the first vaccination events.

Conclusions and Relevance

This trial found null direct effects on COVID-19 vaccination uptake and negative effects on booster uptake among individuals who did not receive but were indirectly exposed to the financial incentives. The timing of this spillover suggests that cohabitants of financial incentive recipients postponed booster vaccination, thereby undermining the potential effectiveness of this policy.

Trial Registration

ISRCTN identifier: ISRCTN59503725.

The power of the family in times of pandemic: Cross-country evidence from 93 countries

The majority of the hospitalizations and deaths associated with COVID-19 occurred in people over the age of 65. In addition, previous studies have shown that intergenerational contacts played a key role in COVID-19-related infection and fatality. This paper utilized two large-scale multinational surveys to uncover the important role of family ties in infection prevention across 93 countries. Using the World Values Survey, we measured country-level family ties emphasizing respondents' view of their parents. We elicited individual willingness to uptake infection prevention measures from a panel study conducted each month in the early phase of the COVID-19 pandemic between March 2020 and July 2021. We find that in countries with stronger family ties, people show more support for non-pharmaceutical interventions and higher vaccine acceptance; moreover, young people are more supportive of mandatory vaccination. The association between strength of family ties and compliance with infection prevention measures was salient before COVID-19 vaccines became available and was persistent before the global vaccination coverage reached 25%.

Megastudy shows that reminders boost vaccination but adding free rides does not

Encouraging routine COVID-19 vaccinations is likely to be a crucial policy challenge for decades to come. To avert hundreds of thousands of unnecessary hospitalizations and deaths, adoption will need to be higher than it was in the autumn of 2022 or 2023, when less than one-fifth of Americans received booster vaccines1,2. One approach to encouraging vaccination is to eliminate the friction of transportation hurdles. Previous research has shown that friction can hinder follow-through3 and that individuals who live farther from COVID-19 vaccination sites are less likely to get vaccinated4. However, the value of providing free round-trip transportation to vaccination sites is unknown. Here we show that offering people free round-trip Lyft rides to pharmacies has no benefit over and above sending them behaviourally informed text messages reminding them to get vaccinated. We determined this by running a megastudy with millions of CVS Pharmacy patients in the United States testing the effects of (1) free round-trip Lyft rides to CVS Pharmacies for vaccination appointments and (2) seven different sets of behaviourally informed vaccine reminder messages. Our results suggest that offering previously vaccinated individuals free rides to vaccination sites is not a good investment in the United States, contrary to the high expectations of both expert and lay forecasters. Instead, people in the United States should be sent behaviourally informed COVID-19 vaccination reminders, which increased the 30-day COVID-19 booster uptake by 21% (1.05 percentage points) and spilled over to increase 30-day influenza vaccinations by 8% (0.34 percentage points) in our megastudy. More rigorous testing of interventions to promote vaccination is needed to ensure that evidence-based solutions are deployed widely and that ineffective but intuitively appealing tools are discontinued.

Nudging towards COVID-19 and influenza vaccination uptake in medically at-risk children: EPIC study protocol of randomised controlled trials in Australian paediatric outpatient clinics

INTRODUCTION

Children with chronic medical diseases are at an unacceptable risk of hospitalisation and death from influenza and SARS-CoV-2 infections. Over the past two decades, behavioural scientists have learnt how to design non-coercive 'nudge' interventions to encourage positive health behaviours. Our study aims to evaluate the impact of multicomponent nudge interventions on the uptake of COVID-19 and influenza vaccines in medically at-risk children.

METHODS AND ANALYSES

Two separate randomised controlled trials (RCTs), each with 1038 children, will enrol a total of approximately 2076 children with chronic medical conditions who are attending tertiary hospitals in South Australia, Western Australia and Victoria. Participants will be randomly assigned (1:1) to the standard care or intervention group. The nudge intervention in each RCT will consist of three text message reminders with four behavioural nudges including (1) social norm messages, (2) different messengers through links to short educational videos from a paediatrician, medically at-risk child and parent and nurse, (3) a pledge to have their child or themselves vaccinated and (4) information salience through links to the current guidelines and vaccine safety information. The primary outcome is the proportion of medically at-risk children who receive at least one dose of vaccine within 3 months of randomisation. Logistic regression analysis will be performed to determine the effect of the intervention on the probability of vaccination uptake.

ETHICS AND DISSEMINATION

The protocol and study documents have been reviewed and approved by the Women's and Children's Health Network Human Research Ethics Committee (HREC/22/WCHN/2022/00082). The results will be published via peer-reviewed journals and presented at scientific meetings and public forums.

TRIAL REGISTRATION NUMBER

NCT05613751.

Reminders, but not monetary incentives, increase COVID-19 booster uptake

Despite substantially decreasing the risk of hospitalization and death from COVID-19, COVID-19 booster vaccination rates remain low around the world. A key question for public health agencies is how to increase booster vaccination rates, particularly among high-risk groups. We conducted a large preregistered randomized controlled trial (with 57,893 study subjects) in a county health system in northern California to test the impact of personal reminder messages and small financial incentives of $25 on booster vaccination rates. We found that reminders increased booster vaccination rates within 2 wk by 0.86 percentage points (P = 0.000) or nearly 33% off the control mean of 2.65%. Monetary incentives had no additional impact on vaccination rates. The results highlight the potential of low-cost targeted messages, but not small financial incentives, to increase booster vaccination rates.