Addressing Vaccine Hesitancy Using Local Ambassadors: A Randomized Controlled Trial in Indonesia

"In settings where resistance and rampant misinformation against vaccines exist, the prospect of containing infectious diseases remains a challenge. Can delivery of information regarding the benefits of vaccination through personal home visits by local ambassadors increase vaccine uptake?"

Hesitancy against vaccination has impeded progress in meeting the Indonesian government's COVID-19 vaccine goals, especially among those in rural areas. This article describes an initiative to conduct a door-to-door randomised information campaign to reach COVID-19 unvaccinated individuals in West Java, rural Indonesia. Organisers recruited ambassadors from local villages tasked to deliver information about COVID-19 vaccines and promote vaccination through one-on-one meetings, using an interpersonal behavioural change communication approach. To investigate which type of ambassador - health cadres, influential individuals, and laypersons - is the most effective, the study randomly varied the type of ambassador delivering the information at the village level.

In the study setting, the interpersonal communication approach was deemed to be more suitable than virtual-information interventions for three reasons:

• Personal visits can reach elderly people, a vulnerable group that is relatively harder to reach by virtual media. In this study, approximately 40% of the respondents are 55 years old and older.
• An in-person interaction is likely to be more effective than a one-way virtual information transmission in terms of generating empathy and connection; in particular, it allows ambassadors to clarify some key facts about vaccines.
• The impact of some forms of virtual interventions, such as text messages, on promoting COVID-19 vaccines has been found to be limited, even in earlier phases of the pandemic.

The intervention was implemented among 3,254 unvaccinated adult individuals spread across 279 villages in three districts (Bogor, Cirebon, and Kuningan) in West Java in mid-June 2022. It involved:

• Treatment 1 (health cadres): Health cadres, unlike professional health workers (e.g., medical doctors), are volunteers operating at the village level who generally do not have medical or nursing degrees.
• Treatment 2 (nominated): Respondents were asked to nominate three individuals whom they perceive as the most respected, trusted, and credible at disseminating health or important information in their village.
• Treatment 3 (layperson). For this treatment, the researchers coordinated with village officials to have an open recruitment or create a list of candidates for layperson ambassadors.

The researchers trained these ambassadors to communicate with consistency, compassion, and empathy. This communication approach is thought to be not only essential to convince people to get vaccinated but is especially important for encouraging individuals who are reluctant to vaccinate due to concerns over their personal rights.

The ambassadors disseminated information and promoted vaccination in two personal 30-minute home visits one week apart. To help amplify the effects of the information session, the ambassadors also distributed a pamphlet summarising information delivered during the information session, such as the importance of vaccines for altruism (e.g., being vaccinated can help contribute to the improvement of community well-being) and personal freedom (e.g., unvaccinated people cannot travel on airplanes). Responses from the endline survey reveal that 83% of respondents were visited by the ambassadors. This proportion is higher for respondents in the health cadres group (91%) than that in the nominated (81%) and layperson (75%) groups.

The researchers opted not to have a control group - one that does not receive a COVID-19 ambassador intervention - in this study for two reasons. First, they consider excluding villages from receiving information about the COVID-19 vaccine to be unethical. Second, it was almost unlikely that they could have a "pure" control group in this setting because our the population probably had received some form of direct information about COVID-19 vaccines from the government task force officers or even police/military forces.

The researchers conducted the baseline survey between February and April 2022 and the endline survey between August and September 2022. The study found three main results:

1. The intervention corrected some misconceptions about COVID-19 vaccines. For example, across the treatment groups, there was a sharp drop in the proportion of individuals reporting fear of side effects (12% to 25%) as the reason for not vaccinating.
2. Participants perceived nominated ambassadors - half of whom were village officials - to be better at delivering the information about vaccines than the other two types of ambassadors.
3. Overall vaccine uptake, registration, and intent were rather moderate (uptake was about 3.6% and registration 7.8%), and the impact of the intervention on vaccination outcomes did not differ across ambassador groups. This is likely because there is no differential impact of the intervention on knowledge and beliefs about COVID-19 across the groups, suggesting that while nominated ambassadors were perceived as being more effective, the information they transmitted was not better retained and acted upon by participants. Some subgroups (females and respondents of low socio-economic status) exhibited stronger vaccine uptake/registration treatment effects of health cadre ambassadors relative to layperson ambassadors.

The researchers offer several possible explanations as to why the intervention did not increase COVID-19 vaccine uptake/registration and why the type of ambassador seems not to have mattered. For instance:

• The results highlight the challenge of boosting vaccine uptake in late stages of a pandemic. The baseline survey took place more than a year after the first vaccination rollout (January 2021) and two years after the first official COVID-19 case. The intervention was launched two months following the baseline. At this stage, the vaccination rate (1st dose) in the focus population of study areas had exceeded 70%. As a result, the sample primarily included individuals who might have been long exposed to both accurate and misleading information as well as encouragement to vaccinate but remained unvaccinated. To address this challenge, the researchers designed the study with a more personal information delivery and encouragement by local ambassadors. However, the population of the study was likely very hesitant.
• There is some indication that individuals in the sample became less concerned about the pandemic over time, as indicated by a drop in the propensity to actively seek information related to COVID-19. There was a notable shift in terms of COVID-19 news consumption: The proportion of respondents who reported almost-daily consumption of COVID-19 news dropped from 33% at the baseline to 13% at the endline, while monthly news consumption increased from 16% to 40%. This is perhaps not surprising because COVID-19 cases in Indonesia also dropped significantly during that period.

"All in all, unlike previous related studies that were conducted in earlier stages of the pandemic, the evidence...suggests that information campaigns in any form - virtual or in-person - might not be very effective in promoting vaccination among very hesitant individuals, especially when the infectious disease incidence has been falling and the immunization coverage is high. In such circumstances, it may be necessary that more directive policies, such as vaccine mandates may need to be considered."