Would COVID-19 vaccination willingness increase if mobile technologies prohibit unvaccinated individuals from public spaces? A nationwide discrete choice experiment from China.

Achieving COVID-19 community protection (aka, herd immunity) in China may be challenging because many individuals remain unsure or are unwilling to be vaccinated. One potential means to increase COVID-19 vaccine uptake is to essentially mandate vaccination by using existing mobile technologies that can prohibit unvaccinated individuals from certain public spaces. The "Health Code" is a ubiquitous mobile phone app in China that regulates freedom of travel based on individuals' predicted risk of exposure to SARS-CoV-2. Green-colored codes indicate ability to travel unrestricted in low-risk regions; yellow-colored codes indicate prohibition from major public spaces and modes of public transportation. We examined the effects of a "Health Code"-based vaccine mandate on willingness to vaccinate for COVID-19 in China. In August 2020, an online discrete choice experiment (DCE) was conducted among adults living in China. Participants completed up to six DCE choice sets, each containing two hypothetical COVID-19 vaccination scenario choices and a "do not vaccinate" choice. Half of the choice sets had a "Health Code" attribute that associated the "do not vaccinate" choice with a yellow Health Code implying restricted travel. Weighted, mixed effects multinomial logit regression was used to estimate preference utilities and predicted choice probabilities. Overall, 873 participants completed 4317 choice sets. Most participants attained at least college-level education (90.9%). 29.8% of participants were identified as vaccine hesitators (defined as being unsure or unwilling to receive a COVID-19 vaccination). With and without the "Health Code"-based vaccine mandate, there was an 8.6% (85% CI: 6.4% − 10.92%) and 17.3% (85% CI:13.1% − 21.6%) respective predicted probability that vaccine hesitators would choose "do not vaccinate" over a common vaccination scenario currently in China (i.e., free, domestic vaccine, 80% effectiveness, 10% probability of fever side-effects, administered in a large hospital, two doses). Corresponding predicted probabilities for people who did not express vaccine hesitancy was 0.3% (93% CI: 0.0% − 14.3%) and 3.5% (93% CI:2.3% − 4.8%). The "Health Code"-based mandate significantly increased willingness to vaccinate when vaccine efficacy was greater than 60%. Among vaccine hesitators with higher educational attainment, willingness to vaccinate for COVID-19 appears to increase if mobile technology-based vaccine mandates prohibit unvaccinated individuals from public spaces and public transportation. However, such mandates may not increase willingness if perceived vaccine efficacy is low. [ABSTRACT FROM AUTHOR]