COVID-19 疫情對美國疫苗猶豫的影響

Abstract

自從 2019 年 COVID-19 爆發後病毒迅速擴展到全球，導致一場持續性嚴重的疫情傳染，死亡率很高。各國為降低疫情帶來的影響，在疫情爆發之初就致力於疫苗研發，以因應這突如其來的災難。特別是美國受到該疫情影響甚巨，根據世界衛生組織2020年的統計，美國累計 COVID-19 確診病例數居世界各國之首。此外，由於美國是世界最大的經濟體，世界經濟也深受打擊。美國積極投入COVID-19 疫苗的研發生產並發揮主導作用，因此，疫苗很早就釋出，並提供足夠的可用劑量。然而，許多人對疫苗接種猶豫不決，導致美國的接種率相對較低。對此，我們更想了解週邊疫情的嚴峻程度，是否會讓人更願意面對疫苗緊急授權生產過程帶來的安全與有效性風險，從而更願意接種疫苗。 本論文分析了美國縣級的疫苗猶豫情況。分析各縣疫情擴散嚴峻程度對接受 COVID-19 疫苗意願的影響。然而，由於影響疫苗猶豫的未觀察到因素，最小平方法迴歸估算有遺漏變數偏誤，使用兩階段最小平方法解決內生性問題。我們的估算結果表明，當時各縣疫情擴散的嚴峻程度會影響個人接種疫苗的意願。

Since the COVID-19 outbreak in 2019, the virus spreaded to the whole world quickly, leading to a persistent and severe epidemic transmission with a high mortality rate. In order to reduce the impacts of the epidemic, countries have committed to the development of vaccines during the initial outbreak of the epidemic to respond this sudden disaster. In particular, the United States was seriously affected by the epidemic. According to the statistics of the World Health Organization in 2020, the cumulative number of COVID-19 confirmed cases in the United States ranked first among all countries in the world. In addition, since the United States was the largest economy in the world, the world economy was also deeply hit. The United States has actively invested in the research and production of COVID-19 vaccines and played a leading role. Therefore, the vaccine was released quite early with sufficient doses available. However, many people were hesitant about vaccination, resulting to a relatively low take-up rate in the United States. In this regard, we are curious to understand whether the severity of the surrounding epidemic would make people more willing to face the risks of safety and effectiveness brought about by the emergency authorized production process of vaccines, and hence more willing to get vaccinated. This paper analyzes vaccine hesitancy at the county level in the United States. It analyzes the impact of the severity of the epidemic transmission in each county on the willingness to receive COVID-19 vaccines. However, due to unobserved factors that affect vaccine hesitancy, the least squares method (OLS) regression estimation has omitted variable bias. The endogenous problem is solved by using the two-stage least squares method (TSLS). Our estimation indicates that the severity of the epidemic spread in each county at that time would affected individual willingness to be vaccinated.