Covid-19 Vaccine Acceptance and Uptake in Bangkok, Thailand: Cross-Sectional Survey via Social Media.

Abstract

The third, most severe COVID-19 wave in mid-2021 coincided with dual challenges of limited vaccine supply and lagging acceptance in Bangkok, Thailand. Understanding of persistent vaccine hesitancy during the "608" campaign to vaccinate the over 60 years and eight medical risk groups was needed. On-the ground surveys place further demands on resources and are scale-limited. We leveraged the University of Maryland COVID-19 Trends and Impact Survey (UMD-CTIS) - a digital health survey conducted among daily Facebook user samples - in this this densely populated, high-transmission region with high Facebook social media use to fill this need and inform regional vaccine roll-out policy. The aims of this study were to characterize COVID-19 vaccine hesitancy, frequent reasons for hesitancy, mitigating risk behaviors, and most trusted sources of COVID-19 information through which to combat vaccine hesitancy in Bangkok, Thailand during the "608" vaccine campaign. UMD-CTIS is an online, cross-sectional survey conducted among daily, statistical samples of the Facebook active user base. We analyzed 34,423 Bangkok UMD-CTIS surveys conducted June-October 2021 coinciding with the third COVID-19 wave. Sampling consistency and representativeness of the UMD-CTIS respondents were evaluated by comparing distributions of demographics, 608 priority groups, and vaccine uptake over time with source population benchmark data. Estimates of vaccine hesitancy in Bangkok and 608 priority groups were tracked over time. Frequently cited hesitancy reasons and trusted information sources were identified by 608 group and degree of hesitancy. Kendall's Tau was used to test statistical associations between vaccine acceptance and vaccine hesitancy. UMD-CTIS Bangkok respondents had similar demographics over weekly samples and compared to the Bangkok source population. Respondents self-reported fewer pre-existing health conditions such as chronic kidney disease and cardiovascular disease compared to census but had similar prevalence of the important COVID-19 risk factor diabetes. UMD-CTIS vaccine uptake rose in parallel with national vaccination statistics, while vaccine hesitancy and degree of hesitancy declined [-7% hesitant per week]. Concerns about vaccination side effects (63%) and wanting to wait and see (62%) were selected most frequently, while "not liking vaccines" (7%) and "religious objections'' (1%" least so, regardless of risk group, time period, or level of vaccine acceptance. Greater vaccine acceptance was associated positively with wanting to "Wait and See'' and negatively with "Don't Believe I Need [the vaccine]" (Kendall's Tau 0.21 and -0.22, respectively, adjusted P values <0.001). Scientists and health experts were most frequently cited as trusted COVID-19 information sources (97%), even within the "Probably Not" and "Definitely Not" groups. These findings provide policy and health experts with evidence that vaccine hesitancy was declining, albeit slowly, over the study timeframe. Hesitancy and trust analyses among the unvaccinated support Bangkok policy measures to address vaccine safety and efficacy concerns through health experts, rather than government or religious officials. Large-scale surveys enabled by existing, widespread digital networks, offer an insightful, minimal-infrastructure resource for informing region-specific health policy needs.