Kawata Keisuke, Nakabayashi Masaki
Institute of Social Science, The University of Tokyo, Hongo 7-3-1, Bunkyo, 103-0033, Tokyo, Japan.
SSM Popul Health. 2021 Aug 24;15:100902. doi: 10.1016/j.ssmph.2021.100902. eCollection 2021 Sep.
Vaccination is a critical measure for containing the COVID-19 pandemic. We survey the determinants that affect the preference for COVID-19 vaccines in Japan, a vaccine hesitant nation.
We conducted a randomized conjoint analysis survey of the preference for vaccines on the Internet by recruiting a nonprobability sample of 15,000 Japanese adults. The survey assigned 5 choice tasks to the respondents. In each task, the respondents evaluated 2 hypothetical COVID-19 vaccines and were asked which they would choose. The vaccine attributes included efficacy, major and minor adverse side effects, country of vaccine development and clinical trial, and vaccine type.
The choice task asked the participants to select a vaccine from 2 hypothetical vaccines as an optional vaccine or select a vaccine as mandated one with a probability of 0.5 for each.
Compared to China-developed vaccines, domestically developed or US-developed vaccines raised the choice probability by 37.3 and 27.4 percentage points, respectively. A domestic clinical trial increased the choice probability by 14.8, an increase in efficacy from 50% to 90% increased that by 18.0, and a decrease in the risk of severe adverse side effects from 1 per 10 thousand to 1 per 1 million increased that by 16.9 percentage points, respectively. The vaccine type was irrelevant. Making vaccination compulsory increased the choice probability of China- and Russia-developed vaccines by 0.6 and 0.4, high-risk vaccines by 0.5, and a modestly effective (70%) vaccine by 0.4 percentage points, respectively. General vaccination hesitancy, political positions, demographic characteristics, education, and income were irrelevant.
A domestically developed vaccine with a domestic clinical trial could substantially increase the preference for the vaccine. Making vaccination compulsory could modestly reduce the penalty for a vaccine with adverse side effects, geopolitical, and efficacy concerns, possibly through mitigating free-riding concerns to achieve herd immunity.
疫苗接种是遏制新冠疫情的关键措施。我们调查了在日本这个存在疫苗犹豫情况的国家中，影响新冠疫苗偏好的决定因素。
我们通过招募15000名日本成年人的非概率样本，在互联网上对疫苗偏好进行了随机联合分析调查。该调查为受访者分配了5个选择任务。在每个任务中，受访者评估2种假设的新冠疫苗，并被问及会选择哪一种。疫苗属性包括效力、主要和次要不良反应、疫苗研发及临床试验的国家以及疫苗类型。
选择任务要求参与者从2种假设疫苗中选择一种作为可选疫苗，或者以各0.5的概率选择一种作为强制接种疫苗。
与中国研发的疫苗相比，国内研发和美国研发的疫苗分别将选择概率提高了37.3和27.4个百分点。国内临床试验使选择概率提高了14.8个百分点，效力从50%提高到90%使选择概率提高了18.0个百分点，严重不良反应风险从万分之一降至百万分之一使选择概率提高了16.9个百分点。疫苗类型无关紧要。强制接种疫苗分别使中国和俄罗斯研发的疫苗的选择概率提高了0.6和0.4个百分点，高风险疫苗提高了0.5个百分点，中等效力（70%）的疫苗提高了0.4个百分点。总体疫苗犹豫、政治立场、人口特征、教育程度和收入无关紧要。
在国内进行临床试验的国内研发疫苗可大幅提高对该疫苗的偏好。强制接种疫苗可能会适度降低因不良反应、地缘政治和效力问题而对疫苗产生的抵触，可能是通过减轻搭便车问题以实现群体免疫。
