School of Civil and Environmental Engineering, Cornell University, USA.
Faculty of Economic Sciences, University of Warsaw, Poland.
Soc Sci Med. 2023 Sep;332:116093. doi: 10.1016/j.socscimed.2023.116093. Epub 2023 Jul 21.
In this study, we employ a choice experiment to study individual preferences for COVID-19 vaccines in the US. A unique characteristic of the microdata (N = 5671) is that the survey was conducted in five distinct waves from October 2020 to October 2021. Because of this dynamic feature, it is possible to control for evolving pandemic conditions such as the number of COVID-19 active cases, vaccination uptake, and the frequency of Google searches related to the vaccines. Furthermore, we employ a hybrid choice model to incorporate respondents' attitudes related to their perceived vulnerability to diseases, as well as their perceived health status. The hybrid choice model was extended to incorporate latent classes as well as random effects. We find that the rate of vaccinated individuals in the population actually increases the probability of vaccine hesitancy, and therefore may discourage people to get vaccinated. This may be evidence of free-riding behavior. On the other hand, the number of COVID-19 cases has a positive effect on the probability of getting vaccinated, suggesting that individuals react to the pandemic conditions by taking some protective measures. Google trend data do not seem to have a straightforward effect on the vaccination demand, but it increases consumers' willingness to pay for several vaccine characteristics. With respect to the analyzed attitudes, we find that perceived uninfectability is a significant driver of vaccine hesitancy, probably related to the frequent "natural immunity" argument. In turn, germ aversion has a positive effect on the probability of getting vaccinated as well as on the marginal willingness to pay. Finally, health status has a limited effect on whether the individual will decide to vaccinate or not.
在这项研究中，我们采用选择实验来研究美国个体对 COVID-19 疫苗的偏好。该微观数据（N=5671）的一个独特特征是，调查是在 2020 年 10 月至 2021 年 10 月的五个不同阶段进行的。由于这种动态特征，我们可以控制不断变化的大流行情况，如 COVID-19 活跃病例的数量、疫苗接种率以及与疫苗相关的谷歌搜索频率。此外，我们采用混合选择模型来纳入受访者对疾病易感性和自身健康状况的态度。混合选择模型扩展到包括潜在类别和随机效应。我们发现，人群中已接种疫苗的个体比例实际上会增加疫苗犹豫的概率，从而可能阻碍人们接种疫苗。这可能是搭便车行为的证据。另一方面，COVID-19 病例的数量对接种疫苗的概率有积极影响，表明个体通过采取一些保护措施对大流行情况做出反应。谷歌趋势数据似乎对疫苗需求没有直接影响，但它增加了消费者对几种疫苗特征的支付意愿。关于分析的态度，我们发现，感知不可感染性是疫苗犹豫的一个重要驱动因素，这可能与频繁的“自然免疫”观点有关。相反，厌恶细菌对接种疫苗的概率以及边际支付意愿都有积极影响。最后，健康状况对个体是否决定接种疫苗的影响有限。
