A great deal of attention has recently been focused on America’s undocumented immigrants, a population estimated at around 10 million people (Passel, Capps, and Fix 2004). Much less attention has been paid (in both scholarly and academic circles) to legal immigrants, although in 2010 (the most recent year for which complete data are available), the Department of Homeland Security granted 1,042,625 permanent resident visas. Indeed, since 1994 when the government began to publish the Annual Flow Report, we have granted between 700,000 to around 1,300,000 new legal immigrant visas annually. Legal immigration into the US involves a process of varying length. That is to say, the elapsed time between applying for a permanent resident’s visa and being granted that visa can range from as little as a few months to as long as several years. It is known that the type of visa being applied for (the various types are explained later) accounts for some of the variation in processing length, and also that lost paperwork is a significant factor (Jasso 2011). This study found no evidence of discrimination in regards to the race, skin color, and religion of the survey respondents in terms of the time it took to get their visas processed. The average wait time for visa processing was about 5 years; Mexicans and Filipinos waited longer than immigrants from other countries. For various reasons discussed in the text, our current immigration system has created a twotiered family-based immigrant visa system. That is, the system gives heavy preference to family members of persons who are already legal immigrants. The preferential status of so-called family reunification visas has been a point of controversy in immigration advocacy circles and that controversy is also reviewed.

Vaccine prophylaxis can undoubtedly be classified among the most important medical discoveries of the last century. The World Health Organization estimates that each year vaccinations prevent between two and three million deaths. Despite vaccines’ safety and effectiveness, vaccine hesitancy, the delay or refusal of vaccines despite their availability, is a re-emerging issue in high income countries. In this thesis I examine this issue pre- and post-COVID-19 pandemic, investigating the main predictors of vaccine hesitancy and highlighting the cognitive processes involved in individual's decision-making. In the theoretical section, I rely on contributions from sociology, economics and public health studies to build a framework enlightening the most relevant predictors of vaccine acceptance, the perceived risk of infectious diseases and the trust in the vaccination process. Through recent development in cognitive sciences, I reframe the issue showing the importance of considering the way individuals perceive, process and retrieve information in developing an informed analysis of vaccine acceptance. In the first empirical chapter, I investigate whether it is possible to identify subgroups in the population characterized by different world-views based on different patterns of the relationship between perceived risk and trust measures. I further assess whether such partitioning hides different levels of vaccine acceptance and whether it also entails a mean of social stratification. In the second empirical chapter I further explore how certain cognitive processes, analytic and intuitive cognition, might be connected to a differential in vaccine acceptance. Furthermore, I highlight individuals’ qualitatively complex perceptions of risk, and I suggest how enhancing the attention on cognitive processes and affective concerns might be a key to addressing vaccine hesitancy. In the third empirical chapter, I investigate vaccine hesitancy during the COVID-19 pandemic. I exploit rich comparative longitudinal data and analyze the association between risk perceptions, trust, and willingness to be vaccinated at three different levels: between individuals, between countries and within countries over time. In this chapter, I underline the importance of disentangling the main relationships of this thesis at different levels of analysis, and stress that vaccine acceptance is a multifaceted topic that could involve issues far beyond its own boundaries.